Stains F-Z
(routine stains, immunostains and molecular markers)
Last revised 25 February 2008
Copyright © 2002-2008 PathologyOutlines.com, Inc.
See also CD Marker chapters
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Note: stains/proteins are in alphabetical order, with numbers before letters, and ignoring dashes and spaces
Go to Stains A-E, including general information
F G H I J K L M N O P Q R S T U V W X Y Z
Interpretation: cytoplasmic stain; endothelium acts as a positive internal control
Positive staining (normal): endothelial cells, megakaryocytes, platelets, mast cells
Positive staining (disease): vascular tumors
Micro images: capillary hemangioma of endometrium (fig 2B); cribriform DCIS of breast - fig 2a: Factor VIII staining shows only rare vascular proliferation; 2b: low MIB1 staining; inflammatory breast carcinoma with factor VIII related antigen staining of dermal lymphatics; factor VIII+ endothelial cells in angiosarcoma of breast
Factor XIIIa
Fibrohistiocytic marker
Micro images: fibrohistiocytic proliferation with dermal nevus (fig c); fibrohistiocytic proliferation with melanoma (fig c)
FADD
Fas (CD95) Associated protein with Death Domain
Not the same protein as Fas
Part of Fas and TNFR1 pathways:
In Fas pathway, death domain portion of Fas recruits FADD
In TNFR1 pathway, TNFR1 binds TRADD, which acts as an adaptor protein to recruit FADD
FAS-FADD and TNFR1-TRADD-FADD recruit FLICE to receptor signaling complex, eventually induce apoptosis
FAK
See focal adhesion kinase
Fas
See CD95
Fascin
55 kDa protein that forms tight and stable cytoplasmic bundles with filamentous actin
Fascin-1: most common type; present in specialized cells with extensive surfaces or migratory potential, such as neurons, glia, dendritic cells, macrophages, skeletal and smooth muscle, endothelial cells; not normal epithelial cells
Fascin-2: in retina; fascin-3: in testis
Actin-bundling protein with important role in cell motility and adhesion
Overexpression in tumors often associated with aggressive disease
Positive staining (disease): carcinoma of biliary tract, breast, colon, lung, ovary, pancreas, skin; follicular dendritic cell tumors, Hodgkin’s lymphoma-classic subtype (highly sensitive), interdigitating dendritic cell tumors Langerhans cell histiocytosis, urothelial carcinoma (noninvasive papillary or invasive)
Negative staining: normal epithelial cells, normal urothelium, benign urothelial lesions
Micro images: synovial sarcoma (positive)
References: Hum Path 2005;36:741
Fas ligand
See CD178
Fat stains
See Oil Red O
Fatty acid synthase
Multifunctional enzyme complex at 17q25 involved in de novo synthesis of saturated fatty acids
Catalyzes conversion of acetyl-CoA and malonyl-CoA into long chain fatty acids via NADPH
Inhibitors are being evaluated as potential therapeutic agents due to toxicity to human cancer cells in vitro
Stronger expression in melanoma vs. nevi; higher for melanoma Clark levels IV/V vs. I/II and Breslow thickness 0.75 mm+ vs. < 0.75 mm; also high in congenital melanocytic nevi (Mod Path 2005;18:1107)
Positive staining (disease): carcinoma of breast, colon, endometrium, ovary, prostate; melanoma
Micro images: various cutaneous melanocytic neoplasms
Fc gamma RIIb
Part of t(1;22)(q22;q11) with lambda light chain
Associated with follicular lymphoma
References: more information #1; #2
Ferritin
Micro images: highly malignant adult hepatic blastoma - fig A: ferritin; B: alpha-fetoprotein; C: HepPar1; D: CK8; E: p53; F: beta-catenin
fes
Tyrosine kinase / signal transducer at 15q25-26
FEV
Gene at 2q33 mutated in Ewing’s sarcoma/PNET
fgr
Tyrosine kinase / signal transducer at 1p36.1-36.2
FHIT
Fragile HIstidine Triad gene
Putative tumor suppressor gene
Deleted in tumors of GI, lung, head/neck
FKHR
Fused with PAX7 gene via t(1;13)(p36;q14) in alveolar rhabdomyosarcoma.
FLI-1
Protein is member of ETS family of DNA binding transcription factors; gene is fli-1, present on #11q24
Involved in cellular proliferation, tumorigenesis, embryologic development of blood vessels
90% of Ewing’s sarcoma/primitive neuroectodermal (PNET) tumors have t(11;22)(q24;q12) which results in fusion of EWS to FLI-1
Sensitive and specific for Ewing’s sarcoma/PNET; also sensitive/specific for vascular tumors vs. sarcomas, carcinomas or melanomas (AJSP 2001;25:1061)
Interpretation: call positive if nuclear staining of 10% of tumor cells (usually is >50%) and positive internal controls of endothelial cells and small lymphocytes (AJSP 2001;25:1061)
Note: other vascular tumor markers (CD31, CD34, von Willebrand factor) are membranous or cytoplasmic stains
Note: cytoplasmic staining present in breast epithelium (benign/malignant) and cutaneous eccrine glands
Uses: differentiate Ewing’s sarcoma/PNET of kidney (positive) from blastema predominant Wilms’ tumor (negative); diagnosis of vascular tumors
Positive staining (normal): endothelial cells, T cells, small lymphocytes
Positive staining (disease): Ewing’s sarcoma/PNET, vascular tumors, lymphomas
Negative staining: blastema predominant Wilms’ tumor; carcinomas, melanomas, non-vascular sarcomas; muscle, nerve, fibroblasts
FLICE/MACH
Member of ICE protease family
MACH = Mort1/FADD Associated CED-3 Homolog
Dominant-negative isoforms block both CD95 and TNF induced apoptosis
Apparently is recruited as a proenzyme to the receptor signaling complex by CD95-FADD and TNFR1- TRADD-FADD
Autoactivates in 2 steps: (1) abstraction of one of its two death effector domains (DED) into receptor complex may relieve autoinhibition caused by interaction between two DED domains, which would prime FLICE/MAH for (2) second trans-cleavage activation step, brought about by close proximity of other recruited pro-FLACH/MACH molecules. This would lead to release of active FLICE/MACH
FLT3
Class III receptor tyrosine kinase preferentially expressed on hematopoietic progenitor cells
Activated FLT3 activates signal transduction pathways involved in proliferation of pluripotent and progenitor cells
Internal tandem duplication reported in acute myeloid leukemia (20%), myelodysplasia (3%); D835 mutation present in AML (7%), myelodysplasia (3%), ALL (3%)
References: Archives 2005;129:1299
FMC7
Late B cell differentiation marker
Positive staining: mantle cell lymphoma, hairy cell leukemia, prolymphocytic leukemia
Negative staining: Chronic lymphocytic leukemia
fms
macrophage colony stimulating factor (M-CSF) receptor; also called CSF-1R, at 5q33-34
Promotes proliferation and differentiation of monocytes-macrophages
Mutations cause constitutive receptor transduction; associated with hematopoietic diseases, including myelodysplastic syndrome
Positive staining (normal): macrophages and their precursors
Positive staining (disease): choriocarcinoma, some AML
Focal adhesion kinase (FAK)
Protein tyrosine kinase, 125 kDa, that regulates antiapoptotic signaling
Binding of extracellular matrix molecules to integrins from endothelial cells causes recruitment of signaling molecules src, focal adhesion kinase, phospholipase C-gamma and basic-FGF to focal adhesion complexes, and modulates ability of endothelial cells to respond to growth factors
Positive staining (disease): invasive breast carcinoma (particularly high grade tumors, Mod Path 2005;18:1289), high grade sarcoma
Micro images: FAK+ breast carcinoma (fig 1a)
Fontana-Masson
Melanin stain; difficult to interpret faint staining in sparsely positive cells
Melanin granules reduce ammonia-silver nitrate and turn black
Micro images: melanoma
Formaldehyde induced fluorescence
Demonstrates catecholamines and indolamines
Biogenic amines plus formaldehyde vapors from heating form highly fluorescent derivatives
fos
Protein at 14q21-22 that binds DNA in complex with jun; an immediate early response gene
FRAP
FKBP Rapamycin Associated Protein
Also called mTOR or RAFT
Founding member of the phosphatidylinositol kinase-related kinase family
Sensor of physiological signals that regulate cell growth, including nutrients, cAMP levels, and osmotic stress
Affects transcription, translation, and autophagy.
Ability to mediate osmotic stress response may be via an intermediate mitochondrial dysfunction, Proc Natl Acad Sci USA 2002;99:4319
Fusin
T lymphocyte surface protein and key attachment site for HIV; works with CD4
Receptors that promote exchange of GTP for GDP bound to G alpha subunit, then dissociation of alpha GTP
and G beta gamma from receptor and each other; then alpha GTP or G beta gamma regulate effector protein; then GTP becomes GDP and alpha GDP reassociates with G beta gamma to turn off the signal
Galectin-3
Member of carbohydrate-binding protein family known as lectins
One of 14 galectins, which function as cell receptors for N-acetyl-lactosamine moieties present on most extracellular matrix components)
Also member of the beta-galactoside-binding protein family that plays an important role in cell-cell adhesion, cell-matrix interactions, macrophage activation, angiogenesis, metastasis, apoptosis
Uses: in one study, Gal-3+ with Ki-67 > 6% was associated with parathyroid carcinomas vs. adenomas (Hum Path 2005;36:908)
Positive staining (normal): endothelial cells, peripheral nerve, folliculostellate cells of adenohypophysis
Positive staining (disease): tumors of thyroid, head and neck, liver, colon, prolactinomas; parathyroid carcinoma; rarely in reactive of hyperplastic parathyroid lesions
Micro images: galectin-3 staining in lung squamous and adenocarcinoma
Reference: Mod Path 2005;18:1264 (prognostic significance in lung squamous cell and adenocarcinoma)
Gangliosides
GM1: on intestinal epithelial cell surface; bound by B unit of choleragen (Vibrio cholera toxin)
Gastrin releasing peptide
Appear at weak 15 of gestation
Relatively specific to neoplastic and non-neoplastic endocrine cells of the lung
Gelatinase B
See MMP-9
Gemori methamine silver
See GMS
Giemsa stain
As a hematology stain, works best with alcohol fixed smears
As a histology stain, detects mast cells and microorganisms, such as Giardia or Helicobacter
A "Romanowsky-type" stain, composed of mixtures of methylene blue, azure, and eosin compounds
Methylene blue is a metachromatic stain, meaning that some tissue components (mast cell granules ,cartilage, mucin, amyloid) stain purple and not blue
Glial fibrillary acidic protein (GFAP)
Intermediate filament for astrocytes (normal, reactive, neoplastic)
Positive staining (disease): CNS tumors, colonic schwannoma (AJSP 2001;25:846)
Micro images: myxopapillary ependymoma of broad ligament (fig 8b)
GLUT1
Facilitative glucose transporter; activated by hypoxia-sensing cellular pathways; may sustain cellular metabolism via glycolysis when hypoxia is present
Positive staining (normal): red blood cells, blood-brain barrier, perineurium
Positive staining (disease): various carcinomas, including fallopian tube carcinomas (Archives 2005;129:651)
Negative staining: benign epithelium
GLUT-4
Glucose transporter 4
Highly expressed in mitochondria-rich (oxyphil) cells in normal/neoplastic tissue, including gastric parietal cells, Hashimoto thyroiditis, Hurthle cell adenomas and carcinomas, occasional oxyphil parathyroid hyperplasias, occasional oxyphil parathyroid adenomas, renal oncocytomas, salivary gland oncycytomas, Warthin tumors, hibernomas
Glycophorin A
Also called CD235a
Positive staining: erythroid cells, AML-M6
Negative staining: AML M0-M5, M7
Glycosaminoglycans
Heteropolysaccharides which contain an N-acetylated hexosamine in a characteristic repeating disaccharide unit involving alternate 1,4- and 1,3-linkages consisting of either N-acetylglucosamine or N-acetylgalactosamine
GMS
Gomori methenamine silver
Special stain for detecting fungi and Pneumocystis carini
Stains cell walls and outlines these organisms; may have artefactual background staining
Micro images: Pneumocystis carinii; Cryptococcus neoformans; Coccidioides immitis; Aspergillus fumigatus
Gram stain
Stain to detect and differentiate bacteria
Method:
Apply crystal violet, then iodine, then decolorize by alcohol/acetone, then counterstain by safranin/fuchsin
Gram positive bacteria retain the crystal violet-iodine complex after decolorization, are not counterstained, and appear purple
Gram negative bacteria have a different cell wall structure, don’t retain the crystal violet-iodine complex after decolorization, and so are counterstained by safranin/fuchsin and appear pink/red
Micro images: various organisms #1; #2
Paraffin sections:
Use neutral red instead of safranin; gram negative organisms usually stain poorly because their bacterial wall lipid is removed in tissue processing
Note: with hematoxylin and eosin staining on paraffin sections, bacteria appear as blue rods or cocci regardless of gram reaction; colonies appear as fuzzy blue clusters
Rapid diagnostic strategy for bronchioalveolar lavage samples consists of Gram stain and bacterial ATP assay (Archives 2005;129:78)
Not suitable for burn wound surfaces (Archives 2003;127:1485)
Micro images:
Fungi - Fusarium in peritoneal fluid
Gram positive tissue sections - Bacillus anthracis in CSF; Lactobacillus osteomyelitis; methicillin resistant Staphylococcus aureus (MRSA) pneumonia; Mycobacterium abscessus (soft tissue); Nocardia asteroides
References: J Clin Pathol 1979;32:187, University of Utah method, University of Nottingham method
Granzyme B
Enzyme associated with cytotoxic T lymphocytes; induces apoptosis in target cells of these lymphocytes
Grimelius
Micro images: breast carcinoma - focal Grimelius+ cells in neuroendocrine DCIS; infiltrating ductal carcinoma with focal Grimelius+ cells; Grimelius stain+ colloid carcinoma #1; #2
Gross cystic disease fluid protein 15 (GCDFP-15)
Glycoprotein originally isolated in human breast gross cystic fluid
Positive staining (disease): lobular breast carcinoma (90%), primary breast carcinomas (72%), metastatic breast carcinoma (80%); also salivary gland and prostate carcinoma, apocrine differentiation
Micro images: breast carcinoma metastatic to stomach (fig 3c); neuroendocrine carcinoma of breast #1; #2
Growth factor receptors
Typically have extracellular ligand binding domain, a transmembrane domain and a cytoplasmic domain with a tyrosine kinase domain
Alterations (amplification, mutation, rearrangement) may lead to constitutive activation in absence of ligand.
gstp1
Gene directs formation of glutathione S transferase protein, which detoxifies environmental carcinogens by reduction
Inactivated by hypermethylation
Kidney tumors: stain must have pH between 1.5 and 2.0
Clear cell and papillary renal carcinoma have focal, coarse, droplike staining
Note: hemosiderin in any tumors will also stain positive
Uses: Helpful in distinguishing chromophobe renal cell carcinoma (intensely positive in large percentage of cells with reticular staining) from oncocytoma (usually negative; if positive - fewer cells with less intensity and dustlike staining)
HAM 56
Stains histiocytes, endothelium, adenocarcinoma
Negative staining: osteoclast-like giant cells
Micro images: giant cell tumor of bone - mononuclear cells are positive (fig 1B); giant cell tumor of tendon sheath - mononuclear and giant cells are positive (fig 2B)
Also called TSC1
On 9q34
Mutations cause tuberous sclerosis, an autosomal dominant disease beginning in infancy or early childhood with mental retardation and seizures, angiomyolipomas, subependymal giant cell tumors, cutaneous angiofibromas, cardiac rhabdomyomas, lymphangioleiomyomatosis and multifocal multinodular pneumocyte hyperplasia
Broadly expressed in many organs and tissues, including myometrium and most smooth muscle
Negative regulator of cell cycle – inhibits cell proliferation
Inactivation causes benign neoplasms in patients with tuberous sclerosis complex
HBME
Marker of mesothelial cells, named after laboratory of Dr. Hector Battifora and MEsothelioma
Also positive in various thyroid carcinomas
hc2
Positive in hairy cell leukemia, activated B and T cells, plasma cells
hcg
human chorionic gonadotrophin
Glycoprotein with alpha and beta subunits, used to detect pregnancy
Positive staining (disease): choriocarcinoma, syncytiotrophoblast cells in other tumors
Negative staining: exaggerated placental sites, placental site nodules, placental site trophoblastic tumors, epithelioid trophoblastic tumors
Heat shock proteins
See hsp
Hemosiderin
Hemoglobin breakdown product that contains iron
Heparanase
Expressed in metastatic gastric carcinoma to lymph nodes (95), primary gastric carcinoma (47%), not in normal gastric epithelial cells (Mod Path 2005;18:205)
Degrades heparan sulfate, a principal component of basement membranes, functional receptor complexes that facilitate signal transduction, and the extracellular matrix
Hepatocyte growth factor (HGF)
Only ligand for c-MET
Pleiotropic growth factor that promotes cell proliferation, motility and morphogenesis; also has important roles in normal development, organ regeneration and tumor development
Positive staining (disease): melanoma, melanocytic lesions
Hep Par1 antibody
Hepatocyte Paraffin 1; Also called Hep
Recognizes mitochondrial antigen of hepatocytes
Highly sensitive (92%); negative in higher nuclear grade tumors, AJSP 2002;26:978
Moderately specific; false positive cases were CK7+ or CK20+ (adenocarcinoma), chromogranin+ or synaptophysin+ (neuroendocrine)
Interpretation: granular cytoplasmic staining
Uses: determine hepatocellular origin, particularly in panel with alpha-fetoprotein and CEA or CD10 (canalicular pattern, more specific than Hep Par1)
Positive staining (disease): most hepatocellular carcinomas, some nonhepatocellular carcinomas metastatic to liver
Negative staining: bile duct adenoma
Micro images: highly malignant adult hepatic blastoma - fig A: ferritin; B: alpha-fetoprotein; C: HepPar1; D: CK8; E: p53; F: beta-catenin
HER2
Also called neu, c-erbB2, p185HER2
Proto-oncogene on #17q11-21 for human epidermal growth factor receptor 2
Member of HER/erbB family, which encodes 185 kDa transmembrane tyrosine kinase receptor proteins (also epidermal growth factor receptor, HER3 and HER4), whose activation causes a cascade of intracellular enzymatic pathways, which can cause cell transformation
Overexpression is an independent adverse prognostic factor in several cancers; usually attributed to amplification of HER2 gene
Tumor expression of HER2 is discordant at nuclear, cytoplasm and cell surface levels, which highlights limitations of immunohistochemistry alone (AJSP 2005;29:1125, pancreatic adenocarcinoma)
HER2 - Breast
Expression is regulated by transcription activation in normal breast
Protein overexpression is associated with gene amplification (at 17q21); note - chromosome 17 polysomy without HER2 amplification doesn’t appear to affect HER2 expression (AJSP 2005;29:1221)
Overexpressed in 20-30% of female breast cancers; associated with comedocarcinoma, aggressive tumors, also intraductal tumor spreading (Hum Path 2002;33:21); usually not due to chromosome 17 aneusomy (Mod Path 2002;15:137)
Amplification causes 90% of cases of HER2 overexpression
Amplification determines eligibility for Herceptin (trastuzumab - anti-HER2 antibody) treatment for breast cancer, but only weak / variable association with poorer prognosis /survival) or response to chemotherapy
85% concordance between immunohistochemistry and FISH in breast carcinoma
HER2 is often amplified in ADH and DCIS, suggesting involvement in initiation of breast carcinogenesis (Mod Path 2002;15:116)
Associated with c-myc amplification (Hum Path 2005;36:634)
10% of ER+ DCIS cases were also HER2+ and were high nuclear grade (Mod Path 2005;18:615)
Vulvar Paget’s disease: overexpression is common in primary and recurrent disease (Mod Path 2005;18:354)
Predominantly determined using immunostaining; relevant staining (3+) is strong, complete membranous staining of tumor cells evident at low power; can be confirmed by Fluorescence In Situ Hybridization (FISH, more sensitive but more expensive and difficult to distinguish in situ from invasive lesions) and Chromogenic In Situ Hybridization (CISH, Mod Path 2002;15:657, Mod Path 2005;18:1015)
Compare intensity to 3+ control slide with negative normal epithelium
For node negative patients, FISH and IHC results were generally similar with some discrepant cases (Archives 2001;125:746)
FDA approved assays give comparable results when strictly handled (Archives 2004;128:627)
Staining pattern:
0 (negative) - no staining or membrane staining in <10% of tumor cells
1+ (negative) - faint membrane staining in > 10% of tumor cells; only part of membrane is stained
2+ (weak positive) - weak/moderate complete membrane staining in >10% of tumor cells
3+ (strong positive) - strong complete membrane staining in >10% of tumor cells
IHC stain scores of 0/1+ (negative/weak) or 3+ (strong) are predictive of FISH results (negative and positive amplification respectively); 2+ is not predictive and has significant interobserver variability (Mod Path 2001;14:1079); suggested to perform FISH or PCR for 2+ tests (will occasionally show amplification, PCR accuracy increased by laser-assisted microdissection, AJSP 2003;27:1565; but see Hum Path 2003;34:1043)
GOLDFISH (gold-facilitated autometallographic in situ hybridization): highly reproducible interpretation of scoring (AJSP 2002;26:908)
Interpretation: strong cell membrane staining around entire cell is associated with gene amplification
Micro images: strong (3+) staining #1; #2; #3; #4; #5; #6; 2+ staining #1; #2; weak (1+) staining #1; #2; FISH amplification #1; #2; IHC (3+) vs. FISH; FISH not amplified; HER2+ comedocarcinoma of breast; HER2+ Paget’s disease of breast; ductal hyperplasia, ADH, DCIS and invasive carcinoma; invasive carcinoma; FISH #1; #2; IHC: strong vs. weak staining; CISH #1; #2 (not amplified, amplified, borderline amplification, equivocal signals); #3 (various strengths); CISH and IHC; DCIS with ER and HER2 double immunostaining; membranous staining in intraepidermal (c) and invasive (d) Paget’s disease; FISH indicates HER2 amplification in vulvar Paget’s disease (red signal)
Virtual slides: HER2 (0/1+, 2+ and 3+);
References: Mod Path 2001;14:213, Mod Path 2000;13:1239 (FISH correlates with IHC), Mod Path 2000;13:866, Mod Path 2000;13:37, Mod Path 2001;14:677, Archives 2003;127:549 (quality assurance), Hum Path 2005;36:250 (quality assurance)
HHF / HHF-35
Also called muscle actin
Positive staining (normal): smooth and skeletal muscle, pericytes, myoepithelial cells, myofibroblasts
Positive staining (disease): rhabdomyosarcoma
HHV-8
Human herpes virus 8
Gamma herpesvirus identified as an etiologic agent for Kaposi’s sarcoma in 1994
Latently infects endothelial cells, monocytes and B cells in Kaposi’s sarcoma patients
Sensitive but not specific for Kaposi’s sarcoma, due to presence in other tumors (including hemangiomas) in immunocompromised (may be present within intratumoral blood mononuclear cells, Mod Path 2005;18:463)
Associated with 3 HIV associated lymphoproliferative disorders - primary effusion lymphoma, multicentric Castleman’s disease, multicentric Castleman’s disease-associated plasmablastic lymphoma
HIV p24
Micro images: placental staining in HIV+ mothers
HLA-DR (Ia)
Positive staining (disease): AML-M3, AML-M6
HLA-G
Non-classical MHC class I antigen that interacts with NK cells, can present nonamer peptides and binds CD8 analogous to classic HLA class 1 proteins
May play a role in maternal tolerance toward fetal tissue
Sensitive and specific for intermediate trophoblast in all types of gestational trophoblastic tissue (including tumors) in initial study, AJSP 2002;26:914
Focal staining in melanoma, renal cell carcinoma, large cell carcinoma of the lung
Negative staining: cytotrophoblast, syncytiotrophoblast
HMB45
Human Melanoma Black, discovered by Dr. Allen Gown
Monoclonal antibody originally identified from melanoma abstract, recognizes melanosomal glycoprotein gp100
Identifies oncofetal glycoconjugate associated with immature melanosomes and probably related to the tyrosinase enzymatic system, J Histochem Cytochem 1992;40:207
Note: invasive melanomas with paradoxical maturation show at least focal deep HMB-45 reactivity, in contrast to nevi which are negative
Melan-A and MART-1 appear to be superior to HMB-45 in evaluating sentinel lymph nodes for melanoma, AJSP 2001;25:1039
Uses: confirmation of melanoma
Positive staining (normal): junctional melanocytes, scattered mononuclear cells in normal lymph nodes, rare nevus cells
Positive staining (disease): angiomyolipoma, tuberous sclerosis complex components, melanomas (85-90%), soft part sarcomas, sugar tumor of lung, lymphangioleiomyomatosis, pheochromocytomas (30%), pigmented nerve sheath tumors, Spitz nevi, cellular blue nevi
Negative staining: epithelial malignant peripheral nerve sheath tumors, spindle cell melanomas (usually), desmoplastic melanoma (usually), oral mucosal melanomas, adult melanocytes
Note: 50% of HMB45 negative melanoma cells have premelanosomes on EM
Micro images: bladder melanoma-HMB45+; atypical angiomyolipoma - A: HMB45+; B: smooth muscle actin+
hMLH1 and hMSH2
Mismatch repair gene;
Mutations in these genes account for 70% of hereditary nonpolyposis colon cancer cases; also hPMS1, hPMS2, hMSH3 mutations
Inactivation causes high levels of microsatellite instability, which alters the cell’s ability to repair errors normally produced during DNA replication
Inactivation often occurs by methylation of its promoter in colon and gastric cancer
Associated with hereditary nonpolyposis colon cancer (90% of cases) and 15% of sporadic colorectal carcinoma
Homeobox genes
Genes that are similar across species at the nucleotide and amino acid level and determine the body’s basic organization
Produce transcription factors; mutations may cause limbs sprouted from the head
The position of the genes reflects the anterior to posterior site and timing of developmental expression
There are sharp boundaries in expression of these proteins
hox 11
Gene at 10q24, amplified in t(10;14)(q24;q11), seen in 7% of T-ALL
hSNF5/INI1
Inactivation associated with malignant rhabdoid tumors of kidney, atypical rhabdoid and teratoid tumor, as well as congenital disseminated malignant rhabdoid tumor and cerebellar tumor mimicking medulloblastoma, AJSP 2002;26:266
Hsp (heat shock proteins)
Induction of these proteins, by tumor necrosis factor and others, confers resistance to many agents which induce apoptosis in hematopoietic cells
Hsp 27
Expressed in upper epidermal layer of skin
Molecular chaperone involved in regulation of cell growth and differentiation
Reduced expression in some hereditary subtypes of ichthyosis (Hum Path 2005;36:686)
hsp 60
Heat shock protein that functions as a small chaperone
hsp 70
Heat shock protein that complexes with p53
hst-1
Also called k-fgf
Angiogenesis growth factor at 11q13.3
Human mobility group gene A2
Upregulated in uterine leiomyomas (Mod Path 2005;18:179)
Human Papilloma Virus
Also called HPV
Detected via PCR or in-situ hybridization
HPV E6 protein induces p53 degradation by a ubiquitin-dependent pathway; also activates host cell telomerase
HPV E7 protein binds retinoblastoma protein, leading to release of E2F transcription factor, then cell cycle progression; E7 also interferes with p21 inhibition of cdk2, causing stimulation of S phase genes cyclin A and E
HPV E5 has antiapoptotic function
Uses: (a) triage specimens with ASCUS into high or low risk; (b) differentiate endocervical (usually positive) from endometrial (usually negative) adenocarcinoma (AJSP 2002;26:998)
Human placental lactogen
Also called HPL
Positive staining: placental site trophoblastic tumors, exaggerated placental sites
Negative staining: placental site nodules (or focal), epithelioid trophoblastic tumors (or focal)
Hyaluronic acid
Glycosaminoglycan found in lubricating proteoglycans of synovial fluid, vitreous humor, cartilage, blood vessels, skin, umbilical cord
Linear chain of 2500 repeating disaccharide units in specific linkage, each composed of a N-acetylglucosamine residue linked to glucuronic acid
Present in the capsule of beta hemolytic streptococcus, Group A organisms
Inhibitor of Caspase-3-Activated DNase
Caspase-3 substrate that controls nuclear apoptosis
Has two isoforms: functional 45kDa isoform called ICAD-L/DNA fragmentation factor (DFF 45) and 35kDa isoform called ICAD-S/DFF35
ICAD-deficient murine cells are resistant to apoptotic stimuli and lack typical nuclear changes of apoptosis
Colon cancer: essential to apoptosis of colonic cancer cells, Cancer Res 2002;62:2169
ICAM-1
InterCellular Adhesion Molecule 1; also called CD54
See CD54 (in CD Markers chapter)
ICE
Interleukin 1 beta Converting Enzyme; related to ced-3 in C. elegans
Formed from cleavage of pro-ICE; then activates inflammatory cytokine interleukin 1 beta
Has early role is signaling pathway for Fas dependent apoptosis
Nuclear substrates: PARP, U1 RNP (U1-70 kDa), nuclear lamins, DNA dependent protein kinase
Cytoplasmic substrates: protein kinase C delta, actin / other parts of cytoskeleton
Inhibitors: p35 (baculovirus protein), CrmA (poxviral protein), aldehydes; no cellular counterparts known
ICH-1
ICE like protease, encodes 2 transcripts (L & S) which also induce and prevent apoptosis, but appear not to be important in vivo
ICK
Cyclin dependent kinase inhibitor
id2
First transcriptional target of N-myc gene
Neuroblastoma: expression associated with poor outcome, stronger predictor than age < 1 year or number of copies of N-myc gene; Cancer Res 2002;62:301
IGF-II
Expressed in pheochromocytoma and extra-adrenal paragangliomas, as well as some hepatocellular carcinomas
Reference: AJSP 2002;26:945
IgG4
6% of total IgG; least abundant of IgG subclasses
Elevated in serum in allergic or autoimmune disorders
Dysregulation associated with inflammatory pseudotumor (IgG4+ plasma cells) in liver, breast and lung; sclerosing pancreatitis (N Engl J Med 2001;344:732
Positive staining (disease): pemphigus vulgaris, inflammatory pseudotumor, sclerosing pancreatitis
References: Hum Path 2005;36:710 (lung)
Ikb-alpha
Inhibitor of NF KB
Due to its serine phosphorylation, it is ubiquinated, leading to proteosome mediated degradation
Inhibin A
Inhibin is a heterodimeric protein (with alpha and beta subunits) that inhibits or activates pituitary FSH secretion
Serum levels elevated (2x) in women with Down's fetus
Positive staining (normal): Sertoli cells (diffuse and strong), granulosa cells, prostate, brain, adrenal
Positive staining (disease): Sex-cord stromal tumors, including Sertoli cell tumors, adrenocortical tumors, placental and gestational trophoblastic lesions, granular cell tumors of gallbladder and extrahepatic bile ducts (AJSP 2001;25:1200),
some carcinomas
Negative staining: primary ovarian carcinomas (usually)
Micro images: sex cord stromal tumor; adrenocortical oncocytic carcinoma
Inhibin B
Inhibin is a heterodimeric protein (has alpha and beta subunits) that inhibits or activates pituitary FSH secretion
High serum levels associated with granulosa cell tumors of ovary and testes
int-2
“Integration” gene at 11q13
Growth factor similar to basic fibroblast growth factor
Normally expressed only during embryogenesis
int-6
Nuclear protein associated with PML; interacts with the Tax protein product of HTLV-1
Integrins
Family of adhesion proteins with various functions, including major cell surface receptors for extracellular matrix proteins
Membrane glycoprotein heterodimer complexes that are assembled by noncovalent association of alpha and beta subunits, with active and inactive states; currently are 18 alpha subunits and 8 beta subunits, which combine to form 24 different integrins
Alpha subunit has extracellular domain that binds matrix molecules; beta subunit has cytoplasmic domain that interacts with actin cytoskeleton, microfilament-associated proteins and signaling mediators
Functions: (a) homing of progenitor T cells to thymus, (b) differentiation and proliferation of B and T cells in bone marrow, transcription of genes involved in cell-cell contacts and endothelial cell migration
Activated by intracellular bacteria and by extracellular ligand binding
Inhibited by RGD (arginine-glycine-aspartic acid) sequence, which blocks integrins from binding to ligands
Integrin alpha 2b beta 3
Also called glycoprotein IIa/IIIb, fibrinogen receptor
Platelet integrin that induces platelet aggregation
Antibodies to alpha2b beta3 prevent ischemia of percutaneous coronary angioplasty
Integrin alpha 3 beta 2
Fibrinogen forms cross links with this platelet receptor during platelet aggregation
Integrin alpha 4 beta 1
Also called VLA-4
Helps white blood cells migrate during the inflammatory response
Found normally in basal epidermal layer
Found in suprabasal skin during wound healing and psoriasis
Integrin alpha 5 beta 1
Also called CD29, fibronectin receptor
Supports assembly of fibronectin matrix
Integrin alpha 6 beta 4
Have role in tumor cell migration and invasion in vitro
Reduced expression in invasive bladder CA
Principal ligand is laminin-5 protein (component of epithelial basement membrane)
Protein production is characteristic of basal/myoepithelial type of breast carcinoma
Beta4 subunit is only expressed in combination with alpha 6 subunit
Micro images: expression in breast carcinoma
References: Mod Path 2005;18:1165 (prognostic significance)
Integrin alpha v beta 3
Specifically expressed in endothelial cells of newly formed blood vessels
May play a role in central nervous system neoplasms
Positive staining (disease): CNS tumors (particularly ependymomas, Hum Path 2005;36:665)
Integrin beta 2
Also called LFA-1, Mac-1
Present on white blood cells; binds to endothelial proteins
Leukocyte adhesion deficiency type 1: CD18/beta 2 integrin subunit deficiency causes severe leukocytosis, recurrent infections of skin and mucosal surfaces, defective white blood cell adherence, chemotaxis, phagocytosis and bacterial killing
Leukocyte adhesion deficiency type 2: impaired synthesis of fucosylated carbohydrates causes developmental abnormalities, defective neutrophil rolling, leukocytosis, recurrent infections
Interleukins (IL)
Soluble factors which stimulate growth-related activities of leukocytes as well as other cell types
Enhance cell proliferation and differentiation, DNA synthesis, secretion of other biologically active molecules and responses to immune and inflammatory stimuli
Promote survival of resting T cells which do not proliferate in response to IL-2, 4 or 7
IL 2, 4 and 7 receptors share a common gamma chain
Interleukin 2 (IL-2)
Potent inducer of CTLA-4
Potent survival factor for lymphocytes
Interleukin 6 (IL-6)
Induces thrombocytosis by stimulating thrombopoietin
Produced continuously by all mesothelioma cell lines
Micro images: IL6+ producing diffuse deciduoid peritoneal mesothelioma
Invadopodia
Plasma membrane protrusions
IRF4
See MUM1
Iron
Also called hemosiderin (storage iron granules)
See also Hales colloidal iron
Perl’s method (Prussian blue stain): hydrochloric acid releases the protein bound to ferric iron, then potassium ferrocyanide binds with ferric iron to form ferric ferrocyanide, an insoluble blue compound
Hemosiderin may be present in areas of old hemorrhage or be deposited in tissues with iron overload
Hemosiderosis: stored iron does not interfere with organ function vs. hemochromatosis: iron overload associated with organ failure
Micro images: Hemosiderin, liver, iron stain
Isochromosome 12p
Extra copies of 12 p
Increase in number of copies of 12p is associated with tumor progression and treatment failure in germ cell tumors
Associated with elevated levels of parathyroid related peptide (also on 12p)
Positive staining (disease): germ cell tumors (testicular, ovarian), embryonal rhabdomyosarcoma, neuroepithelioma
Family whose members (JAK1-3, Tyk2) are critical for cytokine signaling
Associated with intracytoplasmic portion of cytokine receptors, which serves as docking site for STAT monomers; activated JAK activates and phosphorylates the STAT monomers, which then dissociate, dimerize and migrate to nuclear, where they interact with specific DNA binding elements and activate transcription of cyclin D1, bcl-Xl, bax, bcl2, c-myc, c-Jun, c-kit, and IL-10
Jak3: Janus kinase 3, a tyrosine kinase that activates STAT3 in response to cytokine stimulation
Positive staining (disease): ALK+ anaplastic large cell lymphoma (Hum Path 2005;36:939)
References: Archives 2005;129:990
jun
AP-1 protein
Gene is at 1p31-32; protein product binds DNA in a complex with fos
JunB
At 19p13
Member of Jun family of proteins (also c-Jun and JunD), that are components of AP-1 transcription factor complex, involved in cell proliferation and apoptosis
May bind with CD30 gene promoter
Interpretation: nuclear stain
Positive staining (disease): anaplastic large cell lymphoma (ALK+ or negative; cutaneous or not), classic Hodgkin’s lymphoma, CD30+ diffuse large B cell lymphoma, lymphomatoid papulosis
Negative staining: nodular lymphocyte predominant Hodgkin’s lymphoma, CD30- diffuse large cell lymphoma
Micro images: CD30+ lymphomas; classic Hodgkin’s lymphoma and anaplastic large cell lymphoma
References: Mod Path 2005;18:1365)
Type of immunoglobulin light chain
Kappa/lamba ratio is usually 2:1
Restricted expression of either kappa or lambda suggests monoclonality and a neoplastic process
Micro images: primary localized laryngeal amyloidosis (kappa-left; lambda-right)
Micro images contributed by Leica Microsystems, Biosytems division: myeloma of bone marrow with in situ hybridization staining for kappa (left) and lambda (right) light chains using Kappa Probe (PB0645), Lambda Probe (PB0669) and Bond Polymer Refine Detection
keratin
See Cytokeratin
Ki-67
Labile, nonhistone nuclear protein expressed in G1, S, G2 and M phases of cell cycle, then rapidly catabolized at end of M phase and not detectable in G0 and early G1 cells
MIB-1 is the Ig-G1 against Ki-67 for formalin-fixed, paraffin embedded tissue
A marker of cell proliferation
In invasive breast cancer, staining >10% of cells correlated with malignant gene expression using gene chips (Mod Path 2005;18:374)
Interpretation: nuclear staining determines immunoreactivity, not cytoplasmic staining
Use: determine growth fraction; distinguish melanoma (Ki-67+) from nevus cells (Ki-67-/rare) in melanoma sentinel node biopsy (AJSP 2002;26:1351), distinguish benign and malignant adrenocortical tumors (AJSP 2002;26:1612)
Micro images: Ki-67 staining: A: benign phyllodes tumor/minimal nuclear staining; B: low grade malignant phyllodes tumor with increased Ki-67; C: high grade malignant phyllodes tumor with frequent staining; a: high % staining in invasive breast carcinoma; b: negative control
Contributed by Leica Microsystems: tonsil-intense nuclear staining of proliferating follicular cells
Virtual slides: Ki-67 low and high in invasive ductal carcinoma of breast
Kip1
See p27
KOC
K homology domain containing protein Overexpressed in Cancer
Gene at 7p11.5
Oncofetal RNA binding protein highly expressed in pancreatic carcinoma; binds to and regulates insulin like growth factor II
Involved in post-transcriptional regular of cell proliferation during embryogenesis
Apparently necessary for normal pancreatic embryogenesis
Positive staining (normal): placenta
Positive staining (disease): pancreatic carcinoma (usually strong), severe pancreatic dysplasia; also carcinomas of stomach, colon, lung, soft tissue sarcomas, carcinomas of head and neck, liver and kidney
Negative staining: mild/moderate dysplasia of pancreas, normal pancreas (may have weak background acinar staining)
References: AJSP 2005;29:188
KSHV/HHV8
Kaposi’s Sarcoma-associated Herpes Virus/Human Herpes Virus 8
Associated with Kaposi’s sarcoma, primary effusion lymphoma
Reference: AJSP 2002;26:1363
Kuz
Kuzbanian gene; transmembrane protein required for cells to receive signals inhibiting neural fate
Member of ADAM family (a disintegrin and metalloproteinase domain)
Essential for separating neural and nonneural cells during CNS/PNS development in Drosophila
Type of immunoglobulin light chain
Kappa/lambda ratio is usually 2:1
Restricted expression of either kappa or lambda suggests monoclonality and a neoplastic process
Micro images contributed by Leica Microsystems, Biosytems division: myeloma of bone marrow with in situ hybridization staining for kappa (left) and lambda (right) light chains using Kappa Probe (PB0645), Lambda Probe (PB0669) and Bond Polymer Refine Detection
laminin
Major component on basement membrane, with type IV collagen
Trimeric glycoproteins (at least 11 types) with integrin binding site
Defects in laminin proteins cause skin blistering and myocardial diseases
Antibodies to laminin inhibit lung branching morphogenesis
Production of alpha-1 laminin by epithelial cells and mesenchymal cells depends on extent of mesenchymal and epithelial contact with each other; modulates mesenchymal cell shape
Uses: double immunostaining with cytokeratin is useful to detect microinvasion in VIN or CIN (Archives 2005;129:747)
Micro images: laminin5 expression in normal breast, DCIS and invasive ductal breast carcinoma
LANA
Human herpesvirus-8 (HHV8) Latency Associated Nuclear Antigen
Highly expressed during latent HHV8 infection
Interacts with pRb, which regulates beginning of S phase of cell cycle; also inhibits p53
Presence in serum is associated with developing Kaposi’s sarcoma in immunocompromised individuals
Micro images: LANA+ Kaposi’s sarcoma
Positive staining (disease): HHV8 associated Kaposi’s sarcoma (endothelial and spindle cells, 92% sensitive and highly specific), primary effusion lymphoma, multicentric Castleman’s disease
References: Mod Path 2005;18:463 (LANA vs. HHV8 in Kaposi’s sarcoma)
LCK
Gene at 1p34.3; rarely translocated as t(1;7)(p34;q34) in T-ALL
Lymphocyte specific member of Src family of protein kinases involved in T cell and IL2 receptor signaling, important for antigen induced T cell activation
References: OMIM 153390
Lecithin
Major component of cell membrane, usually outer surface
composed of phosphatidylcholine (phosphocholine and diglyceride)
Lectins
Plant-derived proteins that bind specifically to carbohydrate groups acting as lectin receptors
Ulex europeaus lectin combines with H antigen that corresponds to O blood group
Leder’s stain
Type of enzyme histochemistry
Chloroacetate esterase resists effects of formalin fixation and paraffin embedding
Uses: identify mast cell disorders, myeloid disorders
Positive staining (normal): mast cells, myeloid cells
Leu-7
See CD57 in CD Markers CD 50-99 chapter
Lipid stains
See Oil Red O
Lipochrome (lipofuscin) pigments
Breakdown products within cells from oxidation of lipids and lipoproteins
Also called “wear-and-tear” pigments in heart, liver, CNS, adrenal cortex (zona reticularis), testis interstitium and seminal vesicle
Stains with Sudan black B, long Ziehl-Neelson acid fast, Schmorl's methods
Lipochrome may have strong orange autofluorescence in formalin-fixed, unstained paraffin sections
Micro images: Lipochrome in liver, H and E stain
LMP
Latent Membrane Protein of EBV
Interpretation: cytoplasmic or membranous staining
L-myc-1,2
Proto-oncogenes at 1p32 and Xq22-28
L for “lung”, because identified in lung carcinoma
Low affinity nerve growth factor receptor
Marker for adventitial reticular cells in bone marrow stroma
Luke antigen
P blood group system antigen; positive or weakly positive in 98% of patients with Hodgkin’s lymphoma
Luxol fast blue
Myelin stain
Based on strong affinity of copper phthalocyanin dye for phospholipids and choline bases of myelin
lyl-1
Gene at 19p13; rarely translocated as t(7;19)(q35;p13) in T-ALL
Lymphocytes
Two types of T helper cells:
T helper type 1: synthesize interferon gamma and IL-2
Mediates delayed hypersensitivity, activates macrophages, promotes switch from IgM to IgG2a
Stronger TH1 response important for response to leishmaniasis
T helper type 2: synthesize IL-4, 5, 10
Helps B cells, promotes switch from IgM to IgG1 & IgE
Stronger TH2 response important for response to nematodes
Lymphocyte stimulation:
An antigen presenting cell presents a peptide-MHC complex to a T cell; the T cell receptor recognizes this complex, which generates an activation signal to the T cell; a costimulatory signal for nonpolymorphic proteins (CD28 on T cells, CD80/CD86 on antigen presenting cell) is also required
Lysozyme
Also called muramidase
Histiocytic enzyme that cuts muramic acid linkages in bacterial cell walls
Stains histiocytes, neutrophils, and some epithelial cells
Not specific
lyt-10
See NFKB-2
LYVE-1
Lymphatic endothelial hyaluronan receptor-1
Specific marker for lymphatic endothelium (normal or tumor associated)
Use ficin enzymatic retrieval, not heat
Positive staining: squamous mucosa; histiocytes
MACH-1/FLICE
See ICE protease
mad
Mitotic Arrest Defective protein; normally halts mitosis in cells with defective spindles
MAGE
Melanoma AntiGen Encoding gene family
Consists on 19 closely related genes on Xq that encode antigens recognized in vitro by cytotoxic T cells derived from melanoma patients; however, MAGE expression is not specific to melanoma
MAGE-1
Melanoma AntiGen Encoding gene family member 1, also called tumor rejection antigen
May distinguish malignant tumors (positive) from benign tumors (negative)
Uses: distinguish desmoplastic melanoma (positive in 3 of 8) from nerve sheath tumors (weak/negative in 5 of 5), AJSP 2002;26:82
MALT1
Identical to paracaspase, but biologic function is unclear
Part of t(11;18)(q21;q21), producing API2-MALT1 fusion gene in MALT lymphoma
MAPK
Mitogen Activated Protein Kinase
Enzyme important in S phase of cell cycle
Mart-1
Also called Melan-A. A103
Melanocytic Antigen Recognized by cytotoxic T lymphocytes from melanoma patients
Cytoplasmic protein
Sensitive and specific for melanoma
Uses: (1) recommended for sentinel lymph nodes for melanoma (AJSP 2001;25:1039), although also stains benign nevi (AJSP 2002;26:1351); (2) adrenal cortical tumors vs. renal cell carcinoma
Positive staining (disease): primary and metastatic melanomas; epithelioid melanomas, sinonasal melanomas, angiomyolipomas, adrenal cortical tumors, sex-cord stromal tumors, compound nevi, lymphangiomyomas
Micro images: fig 1: adenoma is MelanA+; 2: pheochromocytoma is negative; lentiginous melanoma (a/b); dermal nevus with associated fibrohistiocytic proliferation (fig b); melanoma with fibrohistiocytic proliferation (fig b
Martius scarlet blue trichrome
Stains for fresh (orange-yellow), mature (red) or old (blue) fibrin
Micro images: hepatocellular carcinoma and intravascular tumor - (1) without thrombus - A: H&E; B: Martius scarlet blue; C: factor XIIIa; D: CD34; (2) with thrombus - A: H&E; B: Martius scarlet blue; C: fibrinogen; D: CD34; (3) tumor herniation into vessel wall; A: Martius scarlet blue; B: H&E
mas
Gene at 6q24-27 that produces angiotensin receptor
Maspin
Tumor suppressor protein with serine protease inhibition (Serpin) activity at 18q21.3
Directly regulated by p53; inhibits tumor cell motility, invasion, metastasis and angiogenesis
Cervical squamous cell carcinoma: loss of expression from CIN 3 (HG SIL) to invasive squamous cell carcinoma (Mod Path 2005;18:1102)
Oral squamous cell carcinoma: maspin+ tumors have longer overall survival than maspin- tumors (Oncogene 2000;19:2398)
Positive staining (normal): breast, prostate epithelium
Positive staining (disease): ovarian, pancreatic and gastric carcinomas
Negative staining: breast carcinomas, prostate carcinomas; normal pancreas
Micro images: cervical CIN 3 (HGSIL) and squamous cell carcinoma
Matrilysin
The smallest member of the matrix metalloproteinases
Plays a role in tumor progression.
Matriptase
Also called membrane type serine protease 1 or tumor associated differentially expressed gene-15
Trypsin-like serine protease
Serine proteases are enzymes with uniquely activated serine residue in substrate binding pocket that hydrolyzes peptide bonds; important in digestion (trypsin), blood clotting, fibrinolysis, fertilization and complement activation
Expressed by epithelial elements of almost all organs
Increased expression of matriptase is associated with histopathologic grades of cervical neoplasia (Hum Path 2005;36:626)
max
Protein that forms stable sequence specific DNA binding heterodimer with c-myc
Has basic helix-loop-helix-zipper configuration, typical of DNA binding proteins
May-Grünwald-Giemsa
Used for H. pylori; also blood and bone marrow staining
mcc
See APC
Mutated in Colorectal Carcinoma
mch2
Protein that cleaves nuclear lamins
MCM (MiniChromosome Maintenance proteins)
Drive the formation of prereplicative complexes, the first key event during G1 phase
High levels of MCM2 and MCM5 associated with high grade, high stage, nonpapillary bladder tumors and adverse outcome (Hum Path 2005;36:899)
Interpretation: nuclear stains
MDM2
“Murine Double-Minute 2”
Protein that inhibits p53; gene is at 12q13-15
Amplified in well differentiated liposarcoma and dedifferentiated liposarcoma (amplification detected by comparative genomic hybridization, qualitative PCR, FISH; also immunostain which correlates with gene amplification
Uses: distinguish well differentiated liposarcoma (positive) from benign adipose tumors (negative) and dedifferentiated liposarcoma (positive) from poorly differentiated sarcomas (negative); CDK4 is more specific but less sensitive than MDM2 (AJSP 2005;29:1340)
mdr1
See P glycoprotein
mec1
Mitosis Entry Checkpoint mutant in S. cerevisiae
MEL1
Also called MDS1 / EVI1-like gene
Part of t(1;3)(p36;q21): MEL1 and RPN1
Rarely occurs in myelodysplastic syndrome
Normally expressed in uterus and kidney
Not normally expressed in hematopoietic cells or leukemias that lack this translocation
See Mart-1
Melanin
Pigment normally found in skin, eye, substantia nigra, melanomas
Melanin stains are Fontana-Masson (stains melanin black) and Schmorl’s method (stains melanin blue-green)
Bleaching with potassium permanganate or hydrogen peroxide is used to remove melanin to examine cellular morphology
Note: pseudomelanin of melanosis coli, usually found in macrophages, is PAS positive; true melanin is not
Micro images: Melanin pigment in cells of malignant melanoma, Fontana-Masson stain
Melanoma cell adhesion molecule
See CD146
menin
Gene at 11q13; mutations cause MEN1 syndrome
May regulate transcription of multiple differentiation regulating genes
Menin mutations and allelic loss of 11q13 are also reported in sporadic carcinoid tumors and sporadic pancreatic endocrine tumors
Mesothelin
40 kDa differentiation antigen; precursor protein’s amino portion is megakaryocytic potentiating factor
Cytoplasmic membrane glycoprotein found on surface of mesothelial cells, mesotheliomas, ovarian carcinomas, pancreatic adenocarcinoma
May place a role in cellular adhesion
Positive staining (normal): mesothelial cells
Positive staining (disease): mesotheliomas, ovarian surface carcinomas
Negative staining: benign bile duct lesions
Metalloproteinases (MMP)
Family of neutral zinc metalloenzymes secreted as latent proenzymes, activated by proteolytic cleavage of NH2 terminal domain
Family members degrade collagen and other extracellular matrix proteins
Includes collagenase (degrades collagen types I, II, III), gelatinase (degrades type IV collagen) and stromeolysins
Imbalance between metalloproteinases and their inhibitors (TIMPs) are associated with tumor degradation of the extracellular matrix
mib-1
Ig-G1 antibody against Ki-67
See Ki-67
mic-2
See CD99
Microphthalmia transcription factor (MITF)
Encodes a transcription factor on #3p14.1 essential for development and survival of melanocytes (AJSP 2001;25:51)
Plays key role in transcription regulation of pigmentation enzyme genes tyrosinase and tyrosinase-related proteins 1 and 2
Acts with Ets family factor PU.1 to activate TRAP gene
Heterozygous mutations cause Waardenburg syndrome IIA (autosomal dominant, white forelock and hearing loss)
Interpretation: nuclear immunostaining
Uses: diagnosis of angiomyolipoma (AJSP 2001;25:65), melanoma and other melanogenic tumors
Positive staining (normal): mast cells, melanocytes, osteoclasts
Positive staining (disease): melanomas (including 40% of desmoplastic melanomas), nevi, angiomyolipomas, 66% of clear cell sarcomas, clear cell myomelanocytic tumors of falciform ligament/ligamentum teres
Negative staining: atypical fibroxanthomas, basal cells, neurofibromas, malignant peripheral nerve sheath tumors, palisaded and encapsulated neuromas, melanocytic schwannomas, desmoplastic melanomas (AJSP 2001;25:205), epithelial, smooth muscle, peripheral nerve sheath, fibrohistiocytic lesions (AJSP 2001;25:51), carcinomas and germ cell tumors
Micro images: giant cell tumor of bone - fig 1C: mononuclear cells and giant cells are positive; lentiginous melanoma (fig c)
Microsatellite instability
Changes at (CA)n and (GT)n repeats, associated with dysfunction of DNA repair mechanisms
Involve MLH1, MSH2 proteins
Associated with all cases of hereditary nonpolyposis colorectal cancer and 15% of sporadic colorectal cancers
midkine
Retinoic acid responsive gene for a heparin-binding growth factor.
Mismatch repair defect / microsatellite instability
Hallmark of hereditary nonpolyposis colon cancer (HNPCC) associated tumors is defective mismatch repair, reflect in tumor tissue as microsatellite instability and loss of mismatch repair proteins MLH1, MSH2, MSH6, PMS2
Mismatch repair defects found in 15% of sporadic colorectal cancer in >90% of HNPCC associated cancers
Defects present in 65% of adenomas from HNPCC patients - loss of staining in patient suspected of having HNPCC may be used to direct mutation analysis (Mod Path 2005;18:1095)
Micro images: loss of mismatch repair proteins in adenomas from HNPCC patients with disease causing mutations
MLF1
3q25
Translocated via t(3;5)(q25;q34) in myelodysplastic syndrome/AML
MLH1
Gene mutated in hereditary nonpolyposis colorectal carcinoma and sporadic colorectal carcinoma with microsatellite instability
MMP-1
Matrix metalloproteinase 1, a member of metalloproteinase family of enzymes
Also called collagenase-1, interstitial collagenase
Cleaves alpha chains of types I, II and III collagen, apparently facilitating tumor invasion through collagenous stroma
Expression increased in endothelial cells
Overexpression noted in stroma and epithelium of invasive colonic carcinomas (AJSP 2002;26:206)
MMP-2
Also called type IV gelatinase A
MMP-2 and its inhibitor TIMP-2 are secreted independently and complex extracellularly
Activated by type IV urokinase plasminogen activator when MMP-2 or MMP-9 is bound to cell surface; degraded by same when MMP's are in soluble form
Impaired balance in local levels of MMPs and TIMPs causes extracellular matrix degradation during tumor invasion
Bladder carcinoma: 71% of tumor cells are immunoreactive
Breast carcinoma: imbalance of MMP-2 and TIMP-2 may predict tumor aggression
MMP-3
Also called stromeolysin-1
MMP-9
Also called type IV gelatinase B
Bladder carcinoma: 71% of tumor cells are immunoreactive
MNDA
Myeloid cell Nuclear Differentiation Antigen
Interpretation: nuclear staining
Positive staining (normal): granulocytes, monocytes, myeloid blast cells, activated histiocytes, foreign body giant cells, mantle B (disease): AML, CML, hairy cell leukemia, mantle cell lymphoma, SLL
Negative cells (low level)
Positive staining: non-activated histiocytes, germinal center cells, plasma cells, nonhematopoietic cells
Reference: Hum
Path 1999;30:1040
mos
Proto-oncogene at 8q11, 8q22
Serine-threonine kinase
MPF
M phase Promoting Factor; made up of cdc2 protein kinase and cyclin B
mps1
Required for spindle pole body duplication in G1 and for spindle assembly checkpoint in mitosis
MRP
Multidrug Resistance associated Protein
Levels increased in cells with defective transport of antineoplastic drugs
MRP14
Stains early activated macrophages
MSH1 and MSH2
Genes mutated in hereditary nonpolyposis colorectal carcinoma and sporadic colorectal carcinoma with microsatellite instability
MSN
Also called moesin, Membrane Organizing Extension Spike proteIN
At Xq11, part of t(X;2)(q11;p23)
Cytoskeletal protein that binds to plasma membrane and interacts with actin
References: more information
MTS2
Cyclin dependent kinase inhibitor
Mucins
Also called mucopolysaccharides; major glycoprotein components of mucus under normal circumstances
Large, highly glycosylated proteins with repeat tandem domains rich in serine and threonine sites for O-glycosylation; also contain glyco-conjugates [mucoproteins, glycoproteins, glycosaminoglycans, glycolipids] with high content of sialic acid [N-acyl derivative of neuraminic acid] or sulfated polysaccharide
Neuraminic acid is a 9 carbon amino sugar derived from mannosamine and pyruvate
Mucin stains highlight carbohydrate portion of glycoproteins, not the protein component
Best pan mucin combination may be PAS and Alcian blue
MUC - epithelial mucins, share a common characteristic of an elevated number of sequences repeated in tandem, that are different for each MUC
Two main families of MUC genes – gel forming / secreted mucins at locus 11p15 (MUC2, MUC5AC, MUC5B, MUC6) and membrane-bound mucins at locus 7q22, 3q and 1q21 (MUC1, MUC3A, MUC3B, MUC4, MUC12, MUC13, MUC17)
Mucin types include acid mucins and neutral mucins
Acid mucins: simple non-sulfated, simple mesenchymal, complex sulfated and complex connective tissue types
Acid-simple non-sulfated: contain sialic acid, found in epithelium (gallbladder [benign, adenocarcinoma], intestinal metaplasia in stomach); positive for PAS, Alcian blue at pH 2.5, colloidal iron, and metachromatic dyes. They resist hyaluronidase digestion.
Acid-simple mesenchymal: contain hyaluronic acid and digest with hyaluronic acid, found in tissue stroma and sarcomas. Positive for Alcian blue at pH 2.5, colloidal iron, and metachromatic dyes; negative for PAS.
Acid-complex sulfated: found in adenocarcinomas; usually positive for PAS, Alcian blue at pH 1, colloidal iron, mucicarmine, and metachromatic stains. They resist hyaluronidase digestion
Acid-complex connective tissue: found in tissue stroma, cartilage, and bone; includes chondroitin sulfate, keratan sulfate; Positive for Alcian blue at pH 0.5; negative for PAS
Neutral mucins: GI tract, prostate; stain with PAS only (negative for Alcian blue, colloidal iron, mucicarmine, or metachromatic dyes); note that thyroglobulin and other neutral glycoproteins are also PAS positive
Mucin stains
Alcian blue: stains acid-simple non-sulfated and acid-simple mesenchymal mucins at pH 2.5, acid-complex sulfated mucins at pH 1.0 and acid-complex connective tissue mucins at pH 0.5; does NOT stain neutral mucins
Colloidal iron: acid mucopolysaccharides attract iron particles stabilized in ammonia and glycerin; requires formalin fixation; false positives include phospholipids and free nucleic acids; more specific if hyaluronidase pre-digestion;
stains acid-simple non-sulfated, acid-simple mesenchymal, acid-complex sulfated mucins. Does NOT stain neutral mucins or acid-complex connective tissue mucins
For chromophobe carcinomas, have diffuse strong staining with reticular pattern
Mucicarmine: Very specific for epithelial mucins, including adenocarcinomas; although insensitive; stain contains carmine (red coloring material) and aluminum chloride
PAS (periodic acid-Schiff): stains glycogen as well as mucins, but tissue can be pre-digested with diastase to remove glycogen; stains neutral and acid-simple non-sulfated and acid-complex sulfated mucins; does NOT stain acid-simple mesenchymal mucins and acid-complex connective tissue mucins
Micro images: LCIS of breast
References: AJSP 2005;29:881 (MUC expression in salivary gland mucoepidermoid carcinoma)
MUC1
Epithelial mucin detected in most epithelial tissue; transmembrane or membrane bound
Normally acts as barrier to apical surface of epithelial cells, playing a protective and regulatory role
Inhibits formation of E-cadherin - beta-catenin complex
In breast cancer, aberrant cytoplasmic and membranous localization (associated with micropapillary subtype) is associated with poor outcome (Mod Pathol. 2005;18:1295)
Positive staining (normal): salivary glands, normal type II pneumocytes
Positive staining (disease): breast, pancreatic and colorectal carcinoma; type II pneumocyte lesions (type II cell hyperplasia, dysplastic type II cells, apical alveolar hyperplasia)
Micro images: micropapillary carcinoma of breast; MUC1 staining highlights tumor cell clusters and surrounding clear spaces in breast micropapillary carcinoma #1; #2 in breast and bladder tumors
MUC2
Epithelial mucin expressed in intestinal goblet cells and airway epithelium; gene is at 11p15.5
Relatively specific for predicting colorectal origin for Paget’s disease (AJSP 2001;25:1469)
Gel-forming MUC2 mucin may act as barrier to prevent infiltration of malignant cells in breast mucinous/colloid carcinoma
Positive staining (normal): intestinal and airway epithelium
Positive staining (disease): mucinous carcinomas of colon, breast, pancreas, ovary and stomach
Negative staining: stomach, breast ductal and lobular carcinomas
Micro images: pregnancy related carcinoma
MUC3 (MUC3A and MUC3B)
Upregulated by steroid hormones in vitro
Positive staining (disease): invasive breast carcinoma, gastric carcinoma (associated with poor prognosis)
MUC4
Transmembrane or membrane bound mucin that provides a protective layer of mucus
Normally acts as barrier to apical surface of epithelial cells, playing a protective and regulatory role
Positive staining (normal): tracheobronchial mucosa, colon, stomach, cervix and lung; normal salivary glands
Positive staining (disease): pancreatic, colonic, pulmonary and gastric carcinoma
MUC5AC
Protects epithelium
Positive staining (normal): stomach (foveolar epithelium of body and antrum), tracheobronchial mucosa, endometrium (mucinous metaplasia, eosinophilic change/metaplasia (Mod Path 2005;18:1243), surface syncytial change, ciliated change in 52%)
Positive staining (disease): extramammary Paget disease, but not mammary Paget disease or normal breast tissue (AJSP 2001;25:1469); mucinous carcinoma of ovary, diffuse-type gastric carcinoma (83%)
Negative staining: normal breast tissue
Micro images: poorly differentiated gastric carcinoma - fig 4a: CK20; 4b: MUC5AC; 4c: MUC6; 4d: DAS-1; 4e: CDX2; MUC5AC+ endometrioid endometrial adenocarcinoma (fig 1d); MUC5AC staining in proliferative endometrium with eosinophilic change
MUC6
Produces protective glycoprotein coat for gut epithelia
Positive staining (normal): stomach (pyloric glands), gallbladder, colon and endocervix
Positive staining (disease): invasive ductal carcinoma of breast, gastric carcinomas
Negative staining: normal breast tissue
Micro images: poorly differentiated gastric carcinoma - fig 4a: CK20; 4b: MUC5AC; 4c: MUC6; 4d: DAS-1; 4e: CDX2
MUM1 / IRF4
Transcriptional regulator thought to be involved in T cell activation lineage commitment of lymphocytes and Fas-dependent apoptosis
Also marker for postgerminal center lymphocytes; expressed in the final step of intra-germinal center B-cell differentiation (late centrocyte); apparently in the light zone during centrocyte / follicular dendritic cell contact, when bcl6 expression is downregulated
Responds to interferons and by other cytokines by regulating gene expression, possible of immunoglobulins
Poor prognostic marker in diffuse large B cell lymphoma (signifies non germinal center phenotype)
Also called MSA, HHF35,
Positive staining (disease): leiomyomas, rhabdomyosarcoma; also myofibroblastic, myoepithelial and fibrohistiocytic lesions; also myopericytoma
Negative staining: hemangiopericytoma
MXI1
MaX Interacting protein 1
Negative regulator of Myc oncoprotein
Loss of heterozygosity associated with astrocytomas, glial neoplasia and desmoplastic melanoma
myb
Proto-oncogene found at 6q22-24; also called avian myeloblastosis virus
Binds DNA
Myeloperoxidase
Enzyme cytochemistry for myeloperoxidase (not immunohistochemistry) is the most sensitive and specific stain for myeloid leukemias and granulocytic sarcoma
Stains neutrophils strongly (diffuse granular pattern), other granulocytes variably
Positive staining (enzyme cytochemistry): neutrophils, eosinophils, monocytes (variable), AML-M1, M2, microgranular M3
Positive staining (immunohistochemistry): granulocytic sarcoma
Negative staining (enzyme cytochemistry): lymphocytes, ALL
Micro images: granulocytic sarcoma (immunohistochemistry); myeloid sarcoma of breast (fig 5)
Myelosis
Postulated third form of cell death besides apoptosis and necrosis
Myf-4
Skeletal muscle marker
Nuclear stain
myl
See PML
Myogenic transcriptional regulatory protein expressed early in skeletal muscle differentiation
Sensitive but not specific for rhabdomyosarcoma due to cytoplasmic and non-specific background staining, AJSP 2001;25:1150
Stronger staining in alveolar vs. embryonal rhabdomyosarcomas
Interpretation: nuclear immunostaining
Positive immunostaining (normal): normal fetal muscle
Negative immunostaining: normal adult muscle
Myogenin
Myogenic transcriptional regulatory protein expressed early in skeletal muscle differentiation
Sensitive and specific for rhabdomyosarcoma
Focal nuclear staining in desmoid tumors, infantile myofibromatosis, synovial sarcoma, infantile fibrosarcoma, entrapped atrophic or regenerative skeletal muscle, AJSP 2001;25:1150
Interpretation: nuclear immunostaining
Positive immunostaining (normal): normal fetal muscle
Negative immunostaining: normal adult muscle
Micro images: hepatorenal embryonal rhabdomyosarcoma; desmin (fig4a), myogenin (4b)
Myoglobin
Oxygen binding protein
Positive staining (normal): striated muscle (cardiac, skeletal)
Positive staining (disease): rhabdomyosarcoma, other tumors with skeletal muscle differentiation
Myosin
Contractile protein exists in smooth muscle form (non-sarcomeric) and skeletal muscle form (sarcomeric)
Mediates adhesion of neural crest cells; when these cells stop making N-CAM and N-cadherin and start displaying integrin receptors, cells separate and migrate
Positive staining (normal): neurons, muscle cells, pleural mesothelial cells
N-CAM
See CD56 in CD Markers CD 50-99 Chapter
Nerve growth factor
Produced by Schwann cells, which also produce brain derived neurotrophic factor, ciliary growth factor, glia maturation factor beta
neu
See HER2
NeuN
Nuclear and cytoplasmic staining
Positive staining (normal): mature and immature neurons
Neurofilament
Major cytoskeletal element in nerve axons and dendrites
Consist of three distinct polypeptides, the neurofilament triplet
Metabolism appears to be disturbed in Alzheimer's disease, as indicated by the presence of neurofilament epitopes in the neurofibrillary tangles, and by severe reduction of gene expression for the light neurofilament subunit of the neurofilament triplet in brains of Alzheimer's patients
Positive staining (normal): neuronal cells
Positive staining (disease): central neurocytoma, neuroblastoma, medulloblastoma, retinoblastoma, Merkel’s cell tumor of skin, pancreatic endocrine neoplasms, carcinoid tumors, parathyroid tumors
Neuron specific enolase (NSE)
Cytoplasmic enzyme expressed by neuroendocrine cells/tumors, including poorly differentiated neuroendocrine tumors, which usually are negative for other neuroendocrine markers
Despite its name, is often not specific for neuroendocrine cells/tumors
Enolases are widely distributed glycolytic enzymes that catalyze the interconversion of 2-phosphoglycerate and phosphophenolpyruvate; NSE refers to the gamma-gamma and alpha-gamma isoenzymes preferentially found in neurons and neuroendocrine cells
Positive staining (normal): neurons, neuroendocrine cells
Positive staining (disease): neuroectodermal and neuroendocrine neoplasms; melanomas, other
Images: pheochromocytoma
Neurofibromin
Produces by NF1 gene at 17q11.2
Tumor suppressor gene; member of GTPase activating protein (GAP) family of RAS regulatory proteins
Heterogeneous mutations in neurofibromatosis type 1 (NF1), the most common autosomal dominant inherited disorder in humans (1 per 3000); characterized by benign tumors of peripheral nerves, cafe au lait spots, retinal hamartomas; also increased risk of malignancy, gastrointestinal stromal tumors (AJSP 2005;29:1170)
Downregulates p21 and Ras, and also links integral membrane protein with cytoskeleton; mutations cause constitutive RAS activation
NF 2
At 22q11-13.1; tumor suppressor protein
Produces protein called merlin or schannomin
Deleted in soft tissue perineurioma
Both copies inactivated in up to 60% of sporadic meningiomas
Often no protein expression in schwannoma
May be involved in tumorigenesis of schwannomas and some meningiomas
NFKB
Nuclear Factor Kappa B
Transcription factor that is a heterodimer of p50 and p65/RelA
RelA contains TNF-alpha binding sites
Activated by TNF, radiation, daunorubicin
TNF alpha and IL-1 degrade IKB inhibitory cytoplasmic retention proteins, leading to rapid nuclear translocation of NKFB
Regulates cytokine inducible gene expression, including hemopoietic growth factors, chemokines and leukocyte adhesion molecules
NFKB-2
Nuclear Factor Kappa B 2; also called lyt-10
Gene at 10q24 that binds DNA; translocated as t(10;14)(q24;q32) in 7% of low grade non-Hodgkin’s lymphomas
N-myc
Also called MYCN, gene at 2p24
Amplified gene forms double minutes and homogenously staining regions, and produces excessive N-myc protein
Neuroblastoma: amplification (>10 copies by Southern blot or FISH) associated with poor prognosis and 1p36.3 deletions
Nonspecific esterase
Also called alpha-naphthyl acetate, alpha-naphthyl butyrate
Note: although abbreviation is NSE, is DIFFERENT from neuron specific esterase
Note: opposite staining for alpha-naphthyl chloroacetate esterase
Positive enzyme cytochemistry: monocytes (inhibited by sodium fluoride), AML-M4, M5, mature T cells and T-all (cytoplasmic dot), carcinomas, megaloblastic erythrocytes, cytoplasm focally in AML-M7
Negative enzyme cytochemistry: AML-M0, M1, M2, M3, ALL (usually)
Micro images: IgA myeloma with Auer-rod like inclusions; fig 1: May-Grunwald-Giemsa; 2: α-naphthyl acetate esterase; 3: EM shows Auer-rod like inclusions and rough ER; AML M5b (fig 2)
Notch
Notch signaling pathway plays key role in normal development, differentiation and survival of epithelial cells
Altered in mucoepidermoid carcinomas with t(11;19)(q21;p13)
NPM-ALK fusion protein
Formed by consistent breakpoints in t(2;5)(p23;q35); has truncated NPM and ALK proteins
Contains only constitutively active catalytic domain of ALK
Fusion protein found in anaplastic large cell lymphoma (13-50%); when present, can be used to differentiate from Hodgkin’s lymphoma
Patients with fusion protein appear to have better prognosis
Appears to phosphorylate/activate members of multiple signaling pathways influencing cell proliferation and apoptosis, including ras, Grb2, Shc, IRS-1, JAK/STAT, PI3-kinase/AKT and FOX03a
Nr-CAM
Member of the immunoglobulin superfamily of neural cell-adhesion molecules
Expressed in brain, normal pancreas (acini, weak/none in ducts), increased expression in hyperplasia, reduced expression in poorly differentiated pancreatic tumors, Hum Path 2001; 32:396
Nuclear matrix proteins
Includes peripheral lamins, pore complexes, internal RNA protein network, residual nucleoli
Organizes DNA into loop domains of 60kb, with loop domain bases comprising a site of active gene transcription
Nucleophosmin (NPM)
Also called B23, numatrin; gene at 5q35
Highly conserved non-ribosomal nucleolar phosphoprotein involved in assembling preribosomal particles into small and large ribosomal subunits; binds with high affinity to ss nucleic acids, exhibits activity that destabilizes the RNA helix and is associated with the most mature nucleolar preribosomal ribonucleoproteins.
May contribute active promoter to NPM-ALK; ALK promoter is normally silent in lymphoid cells
Hypothesis: IL-2 or T-cell mediated signals activate substrates; with NPM-ALK, get constitutive activation (note ALCL arises from activated T lymphocytes, which depend on IL-2 for growth and viability)
Fusion protein found in anaplastic large cell lymphoma (13-50%); when present, can be used to differentiate from
Hodgkin’s lymphoma
18 kDa domain transcription factor encoded by POU5F1 gene at 6p21.3
Involved in initiation, maintenance and differentiation of pluripotent and germline cells during normal development
Nuclear stain, highly sensitive and specific for primary intracranial germinomas (AJSP 2005;29:368)
Positive staining (disease): seminoma, embryonal carcinoma, intratubular germ cell neoplasia, ovarian dysgerminoma
Negative staining: spermatocytic seminoma
Oil Red O
Stain identifies neutral lipids and fatty acids
Fresh smears / cryostat sections of tissue are necessary because alcohols used in tissue processing remove lipids
Rapid and simple routine stain
Uses:
(1) differentiate fibroma from thecoma (not that important a distinction)
(2) diagnose renal cell carcinoma, sebaceous gland tumors of skin, lipid-rich carcinomas
(3) identify fat emboli in lung tissue or clot sections of peripheral blood
Micro images: fat emboli in lung
Osteopontin
Alpha (v) beta 3 integrin adhesion molecule
Overexpression in tumors may enhance tumor dissemination by altered cell-cell and cell-matrix interactions and angiogenesis, particularly in breast and colon carcinomas
Osteoprotegerin (OPG)
Inhibitor of osteoclastogenesis
Positive staining (disease): mononuclear stromal cells in giant cell tumors of bone and soft tissue (Hum Path 2005;36:945)
At 9p21, near p16INK4a
Tumor suppressor gene that inhibits CKD4 and CKD6
Hypermethylation associated with progression of myelodysplastic syndrome and leukemic transformation
p16 INK4a
Also called MTS1, CDKN2A; at 9p21 near p15INK4b
Plays crucial role in regulation of G1-S transition
Tumor suppressor gene that inhibits cyclin D dependent protein kinases CDK4 and CDK6, which prevents phosphorylation of Rb, which prevents its dissociation from E2F transcription factor; which prevents cell progression into S phase of cell cycle
Frequently silenced in tumors by epigenetic or genetic abnormalities, including promoter CpG methylation or less often mutations
Cervix: overexpressed in squamous intraepithelial lesions, particularly HG SIL (97% of biopsies, Mod Path 2005;18:267)
ALL (pediatric): homozygous deletions noted in 80% of cases with 9p21 abnormalities
T-ALL: deleted in 80% of all cases (even with normal #9)
Esophageal carcinoma: high frequency of abnormalities
Lymphoma: p16 gene methylation present in 60% of pulmonary MALT lymphomas; may be early event (Mod Path 2005;18:1187); methylation also associated with Hodgkin’s lymphoma, plaque phase of mycosis fungoides, monoclonal gammopathy of unknown significance
Melanoma: abnormalities in 50% of sporadic cases
Pancreatic carcinoma: high frequency of abnormalities
Squamous cell carcinoma, cutaneous: mutations present
Micro images: strong full thickness expression
Molecular images: p16 gene methylation in pulmonary MALT lymphomas
p18 INK4b
Gene at 1p32, related to p16INK4a
p19 ARF
Gene at 9p21, represents alternate splicing of p16INK4a
Lacks homology to INK4a proteins, but can induce cell-cycle arrest
p19 INK4d
Gene at 19p13; related to p16INK4a
p21 WAF1/CIP1
Gene at 6p21.2
Negative cell cycle regulator in G2-M phase and G1-S phase
Regulated transcriptionally by p53
p27 kip1
Cyclin dependent kinase inhibitor leading to cell cycle arrest in G1 phase
Member of Cip/Kip family of proteins
Loss or reduced expression is associated with poor outcome in carcinoma of breast, prostate, GI tract and lung
Interpretation: nuclear stain
p53
Tumor suppressor gene at 17p13, 53 kDa; produces nuclear phosphoprotein involved in transcriptional regulation
Mutations are among most commonly detected genetic abnormalities in human neoplasia
N terminus amino acids bind (a) TAF's, which attract other proteins needed to initiate gene expression, as well as (b) MDM2, which inhibits p53 and has the opposite effect as TAF's
Function: p53 ensures that cells repair any damaged DNA before cell division by inducing cell cycle arrest to allow time for (a) DNA repair or (b) to force the cell to undergo apoptosis via activation of bax gene
Inactivated by SV40 T antigen and E1B adenovirus product; sequestered by HPV E6 protein
Wild p53 induces p21 WAF-1, which inhibits cyclin-dependant kinases
Wild p53 half life only 20 minutes
Detected by immunostains only if mutation causes protein stability (although protein may be nonfunctional) or a physiologic response to (a) genetic changes induced by cellular stress from anoxia or aneuploidy or (b) genetic damage to other pathways controlling p53 such as MDM2 or alternative reading frame
Associated with aneuploidy, increased S phase fraction, genetic instability
B-ALL: 50% are p53 positive
Breast: low p53 levels in ADH, higher frequency in comedo DCIS
Colonic adenocarcinoma: Increased nuclear staining, AJSP 2002;26:206
Li-Fraumeni syndrome: germline heterozygous mutation in p53
Urothelial carcinoma in situ: p53 positive (reactive urothelium is p53 negative), AJSP 2001;25:1074
Interpretation: nuclear stain; usually staining of >5% of nuclei is considered positive
Micro images: strong staining in sarcomatoid carcinoma of respiratory tract of epithelial and sarcomatoid components (Fig 2C), Fig 3B; p53+ malignant phyllodes tumor
Virtual slides: p53+ invasive ductal carcinoma of breast
References: AJSP 2002;26:1024
p57 kip2
Strongly paternally imprinted gene, expressed predominantly from the maternal allele in most tissues
(Genetic imprinting: differential DNA methylation of maternal and paternal alleles leading to allele-specific expression)
Potent cell cycle inhibitor and tumor suppressor
Beckwith-Wiedemann syndrome, complete hydatidiform mole: lack of p57 activity associated with hyperproliferation
Uses: differentiate complete hydatidiform mole (no nuclear DNA of maternal origin, p57 KIP2 underexpressed) vs. partial hydatidiform mole or spontaneous abortion (normal expression), AJSP 2001;25:1225
Positive staining (normal): maternal decidua, intervillous trophoblast islands, spontaneous abortions
Positive staining (disease): partial hydatidiform mole
Negative staining: complete hydatidiform mole
p63
Member of p53 gene family at 3q27-29, but does not appear to be a tumor suppressor gene
Encodes at least 6 different proteins with different biologic functions
Appears to regular growth and development of epithelial organs - germline mutations cause ectrodactyly (missing or irregular fingers or toes), ectodermal dysplasia and facial clefts syndrome, also called limb mammary syndrome (hypoplasia/aplasia of mammary glands and nipple)
May be molecular switch for initiation of “epithelial stratification program”
Gene and protein expression may not correlate due to presence of isoforms and post-translation modification
Main isoforms at TAp63 and deltaNp63; TAp63 activates p53 target genes, but deltaNp63 inhibits transcription activation of p53 gene and transactivating isoforms
TAp63 is highly expressed in most benign tumors; negative/weak in most carcinomas vs. deltaNp63 is negative/weak in most benign tumors and highly expressed in adenoid cystic, mucoepidermoid and myoepithelial carcinomas (Hum Path 2005;36:821)
May be sensitive/specific marker of breast myoepithelial cells (AJSP 2001;25:1054)
Relatively specific for prostate basal cells and may be more sensitive than 34 beta E12/CK903 (AJSP 2002;26:1161)
Positive staining (normal): nuclei of myoepithelial breast cells; also basal epithelium of skin, uterine cervix, urogenital tract, prostate
Positive staining (disease): adenoid cystic carcinoma (not cases with basaloid growth pattern, Mod Path 2005;1277), basal and myoepithelial cells in benign/malignant salivary gland tumors (using anti-full length p63); breast myoepithelioma; discontinuous staining in LCIS and DCIS (AJSP 2001;25:1054)
Negative staining: normal mammary epithelium; breast stromal cells; invasive ductal adenocarcinoma of breast (usually); prostate adenocarcinoma
Micro images: benign epithelial inclusions of axillary lymph nodes - fig 1: CK5/6+; 2: p63+; adenoid cystic carcinoma of breast (fig D, E)
p73
Gene at 1p36.3
p53 homolog that induces apoptosis and inhibits cell proliferation
Frequently deleted in neuroblastoma
Truncated isoform, DeltaNp73, has anti-apoptotic activity, and is associated with reduced survival in some studies
p75
Low affinity nerve growth factor receptor
p140 trkA
Trk gene at 1q32-41
High and low affinity nerve growth factor receptors, expressed by triploid neuroblastomas, with tyrosine kinase activity
p504S
See AMACR
Paired helical filaments
Also called PHF
Combinatin of microtubule associated tau protein, both normal and hyperphosphorylated, forms thin filaments within neuronal cytoplasm; when glycosylated, the filaments become paired and are known as paired helical filament
PARP
Poly (Adenoside diphosphate Ribose) Polymerase, a nuclear enzyme
Involved in DNA repair, genome surveillance and integrity, predominantly in response to environmental stress
Inhibits the Ca/Mg dependent endonuclease
An immediate cellular reaction to DNA strand breakage induced by alkylating agents, ionizing radiation or oxidants; may then mediate DNA base-excision repair; also is an early step in apoptosis due to cleavage by CPP32 (caspase 3), which may lead to loss of its inhibitory effect, promoting apoptosis
Positive staining (disease): melanoma (37%)
Negative staining: normal melanocytes (only scattered, focal staining)
References: Hum Path 2005;36:724 (melanoma)
PAS (Periodic Acid-Schiff)
A special stain, not an immunostain
Theory: substances with nearby glycol groups or their amino or alkylamino derivatives are oxidized by periodic acid to form dialdehydes, which combine with Schiff's reagent to form an insoluble magenta compound
Used for formalin fixed tissue and enzyme cytochemistry; can be used for frozen sections with modifications (Eur J Gynaecol Oncol 1998;19:482. AJSP 1992;16:87)
Stains basement membrane (normal and in tumors), glycogen, some mucins (see below) and mucopolysaccharides
A routine stain in brain (with Luxol fast blue), cornea, kidney, liver and skeletal muscle specimens for nontumor pathology
Some mucins (see below) are PASD (PAS with predigestion with diastase) positive (i.e. stain is present after diastase predigestion; also called diastase resistant); glycogen is PASD negative (also called diastase sensitive because diastase removes PAS staining)
PAS stains neutral and acid-simple non-sulfated and acid-complex sulfated mucins
PAS does NOT stain acid-simple mesenchymal mucins and acid-complex connective tissue mucins
Also stains various inclusions, bodies, granules and secretions composed of mucopolysaccharides or mucins
Uses:
Breast cytology: PASD positive cells with internal structure and producing nuclear indentation, particularly in dissociated or atypical cells, correlate with malignant histology (J Clin Pathol 2001;54:146)
Fungi: stains fungal cell walls; PAS+ granule at anterior end of mature spores is diagnostic of microsporidia (BMC Clin Pathol 2006;6:6)
Hematopathology: ALL, AML M5-M7 are PAS+
Kidney: recommended for routine evaluation of renal biopsies due to basement membrane staining; also useful to diagnose renal cell carcinoma (stains glycogen, removed by diastase)
Liver: routine stain; also stains inclusions of alpha-1-antitrypsin disease
Lung: stains amorphous or granular globules in BAL fluid in pulmonary alveolar proteinosis (J Clin Pathol 1997;50:981)
Muscle biopsies: routine stain to demonstrate glycogen
Pancreas: acinar cell carcinoma (PASD+)
Parotid glands: zymogen granules are PAS+
Prostate: Cowper’s glands are PASD+ (AJSP 1997;21:550)
Skin: eosinophilic globoid bodies (Kamino bodies) in Spitz nevus are PASD+
PAS (continued)
Small intestine: stains Whipple’s disease bacteria (AJCP 2002;118:742, Hum Path 2003;34:589); strong cytoplasmic staining present in microvillous inclusion disease versus linear brush border staining in normals (AJSP 2002;26:902)
Testis: stains intratubular germ cell neoplasia (AJSP 1994;18:947) and seminoma (PAS+, PASD negative), but not normal seminiferous tubules
Tumors: adenocarcinoma of various sites (mucin is PASD+), alveolar soft parts sarcoma (PASD+ crystalline structures), apocrine carcinomas, basement membrane containing tumors (cylindroma [AJSP 2001;25:823], eccrine spiradenoma), clear cell tumors (stains glycogen), glycogen rich carcinomas, glycogen rich/balloon cell melanoma (Archives 1998;122:353), granular cell tumor (cytoplasmic granules), hyaline globules in renal tumors (Hum Path 1997;28:400), mucinous tumors, Paget’s disease of breast
Other: stains malakoplakia
Enzyme cytochemistry: coarse granular staining
Positive staining (normal): basement membrane, fungi, glycogen (removed after diastase or amylase predigestion), mucins (neutral and acid-simple non-sulfated and acid-complex sulfated types), surfactant
Positive staining (disease): ALL (75%, block staining), alpha-1-antitrypsin inclusions, alveolar soft part sarcoma (intracytoplasmic crystals), AML-M5a, M6 (60%), M7, basement membrane containing tumors (cylindroma), clear cell tumors, malakoplakia, renal cell carcinoma (PAS+ glycogen removed with diastase), parasites
Negative staining: mucins (acid-simple mesenchymal and acid-complex connective tissue types)
Micro images:
bacteria - atypical mycobacteria; rhodococcus #1 is PAS+ in colonic histiocytes (far right); #2 in pulmonary histiocytes (PASD+); Tropheryma whipplei in histiocytes in hippocampus (fig 3)
blood and marrow elements - various images; PAS+ megakaryocytes and neutrophils
brain - acquired hepatocellular degeneration (with Luxol fast blue)
breast cytology - PASD+ malignant tumors; PASD “not actually positive” benign tumors
CNS - secretory meningioma PAS+ inclusions #1; #2
colon - malakoplakia (fig 3: PAS, 4: calcium stain)
cornea - Fuch’s dystrophy
PAS (continued)
fungi - blastomyces; candida of esophagus #1; #2; lung; tongue; Coccidioidis immitis of tongue (fig 4); cryptococcal meningitis; histoplasmosis of colon in HIV+ woman (fig 3); microsporidia; mucor #1 of stomach; #2 of skin; ringworm (skin)
heart - glycogen storage disease #1; #2 (removed by diastase)
kidney - normal; Alport’s syndrome #1; #2 (fetal glomerulus); amyloidosis #1; #2; chronic pyelonephritis; dense deposit disease #1; #2; Fabry’s disease #1; #2; focal segmental glomerulosclerosis; Henoch Schoenlein purpura; IgA nephropathy #1; #2; immunotactoid glomerulonephritis; membranoproliferative glomerulonephritis type I #1; #2; with crescent; with doubling of capillary wall; nephronophthisis; nodular glomerulosclerosis #1; #2; #3; SLE #1; #2; #3; #4; thrombotic microangiopathy
liver - alpha-1-antitrypsin deficiency #1; #2; hepatitis A with confluent necrosis
lung - pneumocystis pneumonia; pulmonary alveolar proteinosis: globules (B/D) are PAS+; A/C are H&E; surfactant in hyaline membrane disease
parasites - Acanthamoeba histolytica #1 (colon); #2 (cornea); #3 (brain); Echinococcus (fig 2/3) in bone
parotid gland - normal
skeletal muscle - increased glycogen (PAS+, PASD-) in desmin related myopathy; PAS+ diastase sensitive material in McArdle’s disease #1; #2
skin - Fabry’s disease
small intestine - normal (fig 2), microvillous inclusion disease (fig 3/4)
tumors - acinar cell carcinoma of pancreas; adenocarcinoma of colon; alveolar soft parts sarcoma #1; #2 in cervix; #3; clear cell acanthoma; clear cell carcinoma of ovary; cylindroma #1; #2; eccrine spiradenoma; endolymphatic sac papillary tumor of ear; Ewing’s sarcoma; glycogen rich carcinoma of breast - fig 1/2: infiltrating nests of atypical cells with abundant clear cytoplasm; 3: PAS+ granules; 4: PAS staining is removed by diastase; glycogen rich urothelial carcinoma; granular cell tumor #1; #2 (esophagus); juxtaglomerular cell tumor of kidney; Kaposi’s sarcoma; lymphoplasmacytic lymphoma; mucinous cystadenoma of ovary; Paget’s disease-penis; secretory carcinoma of breast; secretory meningioma; tubulocystic carcinoma of kidney
Virtual slides: cryptococcus of brain
References: Wikipedia, MacManus (Hoslink), Stainsfile
PAX-5
Also called BSAP, a B-cell-specific transcription factor at 9q13
Detected in B cells from pro-B-cell stage to plasma cell stage where it is downregulated
Required for progression of B-cell development beyond the early pro-B cell stage
Uses: detection of pre-B cells, diagnosis of classic Hodgkin lymphoma versus T/null cell anaplastic large cell lymphoma, diagnosis of lymphoplasmacytic lymphoma/plasmacytoid differentiation in marginal zone lymphoma versus plasmacytoma
Positive staining (disease): most B cell malignancies (pre-B and mature B cell lymphomas/leukemias), Hodgkin lymphoma (Reed-Sternberg cells, 97%), lymphoplasmacytic lymphoma, Merkel cell and small cell carcinoma (93% and 73%, AJSP 2005;29:687)
Negative staining: myeloma, plasmacytoma, T cell lymphomas, carcinoid tumors
Reference: AJSP 2002;26:1343
PAX-7
1p36
Transcription factor and member of the PAX family of developmental control genes
Fused with FKHR gene via t(1;13)(p36;q14) in alveolar rhabdomyosarcoma.
PAX-8
9p13; translocated as t(9;14)(p13;q32) in 40% of lymphoplasmacytic lymphoma
B-cell-specific regulator protein
Encoded by paired box gene
PBX1
Gene at 1q23 produces transcription factor with homology to Drosophila homeotic genes
Normally not expressed in lymphocytes
PCA-1
Positive staining: plasma cells
PCNA
Proliferating Cell Nuclear Antigen; also called cyclin
Nonhistone 36 kDa nuclear protein with a role in DNA synthesis, DNA repair, and cell cycle progression
Coordinates synthesis of both leading and lagging strands at the replication fork during DNA replication
Expression correlates with proliferation activity
PDGF
Platelet Derived Growth Factor, also called c-sis
Produced and secreted by megakaryocytes, activated vascular endothelial cells, macrophages, fibroblasts, smooth muscle cells
Composed of combinations of A and B isoforms (AA, AB, BB)
PDGF alpha receptor binds to all 3 isoforms; PDGF beta receptor binds only to BB with high affinity
Chondrosarcoma: high expression of PDGF alpha receptor associated with poorer overall survival, AJSP 2001;25:1520
Ovarian cancer: PDGF alpha receptor expression associated with shorter overall survival
PDGF-A
Potent growth factor for fibroblasts
Expression is inversely related to desmoplasia in desmoplastic small round cell tumors (Mod Path 2005;18:382)
Micro images: H&E and PDGF-A expression in desmoplastic small round cell tumors with variable desmoplasia
PELP1
Estrogen receptor regulatory protein designed ProlinE, Glutamic acid and Leucine-rich Protein 1; also known as modulator of nongenomic activity of estrogen receptor (MNAR)
Forms complex with Src kinase and ER to activate the MAPK pathway
Activates estrogen receptor alpha and beta
Also induces E2 mediated cell cycle progression by interacting with retinoblastoma protein
High levels in most salivary duct carcinomas, compared to normal salivary tissue (Hum Path 2005;36:670)
Pentachrome stain
Stains collagen and mucin in thrombi, plaques
per
Period gene
Works with tim protein to generate oscillating cycle of activity
Cycles up and down every 24 hours
Mutations make circadian rhythm of fly longer/shorter; tim mutations shut down cycling
Circadian rhythm is generated as follows: per protein is relatively unstable, per levels increase slowly, per binds to tim, a more stable dimer; per-tim enters nucleus, shuts down per and tim genes
P glycoprotein
Aka MDR1, multidrug resistance to cancer, CD243
Member of large superfamily of highly conserved ATP binding cassette transport proteins
"Detoxifying agent" that pumps toxins out of cells, also transports steroid hormones
Prognostic importance: correlates with poor response to chemotherapy / shorter survival for osteosarcoma
Positive staining (normal): adrenal cortex, biliary canaliculi, blood-brain endothelium, blood-testicle endothelium, placenta, GI endothelium, proximal renal tubules, some bone marrow stem cells
PGP 9.5
Protein Gene Product 9.5
Neuronal marker
Phosphotungstic acid-hematoxylin (PTAH)
Variant of trichrome stain; demonstrates intracytoplasmic filaments in muscle and glial cells
Micro images: myxopapillary ependymoma of broad ligament (fig 7)
PIK
Kinases which transfer phosphate groups to phosphatidylinositol (PI)
PIK-related kinases
Participate in meiotic & V(D)J recombination, chromosome maintenance and repair, cell cycle progression, cell cycle checkpoints
pim-1
Gene at 6p21 is a serine-threonine kinase
PKD1
Gene at 16p13.3 produces polycystin1; gene is adjacent to TSC2 gene for tuberous sclerosis
Mutations can cause autosomal dominant polycystic kidney disease
PKD2
Gene at 4q22 produces polycystin2
Mutations can cause autosomal dominant polycystic kidney disease
PKD3
Mutations can cause autosomal dominant polycystic kidney disease
PLAG1
PLeomorphic Adenoma Gene 1, at 8q12, often due to t(3;8)(p21;q12) involving CTNNB1 and PLAG1 genes
Proto-oncogene consistently rearranged in pleomorphic adenomas of salivary glands in both epithelial and myoepithelial cells (Mod Path 2005;18:1048)
Micro images: karyotype, FISH and CISH
PLAP
Placental Alkaline Phosphatase
Positive staining (normal): some infantile germ cells until age 1
Positive staining (disease): most germ cell tumors, particularly seminomas; also breast, lung, ovarian carcinomas (some)
Platelet epithelial cell adhesion molecule 1 (PECAM-1)
See CD31 in CD Markers Chapter
PLX-1
Polo Like kinase in Xenopus
Serine threonine kinase
PML
also called myl
Gene at 15q22, overexpressed in all cases of acute promyelocytic leukemia (AML-M3), via t(15;17)(q22;q11-12)
PML-RAR alpha