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Skin / Soft Tissue Tumors

Angiomatoid fibrous histiocytoma

Author: Nat Pernick, M.D., PathologyOutlines.com, Inc.

Reviewer: David Lucas, M.D., University of Michigan Health Systems (January 2009)

Revised: 26 June 2009, last major update June 2009

Definition

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● Uncommon variant with thick pseudocapsule, marked chronic inflammatory infiltrate and cystic areas of hemorrhage

Terminology

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● First described in 1979 (Cancer 1979;44:2147)

● Formerly called angiomatoid malignant fibrous histiocytoma

● May not actually be fibrohistiocytic - Rosai believes origin is vessel related myoid cells with inflammatory features

Clinical

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● Teens/young adults, often on extremities in areas of lymphoid tissue (popliteal fossa, decubital fossa) or neck

● Often fever, malaise, anorexia or paraproteinemia

Case reports

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● 8 year old boy with pleomorphic scalp tumor with minimal angiomatoid or lymphoid features (J Cutan Pathol 2008;35:855)

● 25 year old man with t(12;22) and intracerebral primary (AJSP 2008;32:478)

● 28 year old woman with leg tumor with cystic structures of sweat duct origin (Pathol Int 2007;57:513)

● Mediastinal tumor (Ann Thorac Surg 2001;72:283)

Treatment and prognosis

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● Excision; may recur locally (10%), distant metastases are rare (1%)

Gross description

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● Circumscribed, multinodular or multicystic hemorrhagic mass; median 2 cm, usually subcutaneous

Micro description

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● Thick fibrous pseudocapsule surrounds nodules of monomorphic bland spindle to ovoid eosinophilic cells

● Often highly cellular with hemorrhagic cyst-like spaces, large aggregates of chronic inflammatory cells at edge of tumor in lymphoid follicles

● May have moderate pleomorphism and mitotic activity

Micro images

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Resembles out of place                                    Chronic inflammatory cells and nodules of cells with

lymph node                                                          round / oval nuclei surround hemorrhagic cystic spaces

Cells surrounding cystic                                  Some tumors have                                            Mediastinal tumor

spaces are uniform with                                  moderate pleomorphism

round / oval nuclei

Various images                                                  H&E and desmin

Virtual slide and other

images (USCAP)

Cytology description

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● Histiocyte-like cells in clusters or dispersed

● Eosinophilic mesenchymal fragments in bloody background with lymphocytes

● Tumor cells have moderate pleomorphism with abundant fragile cytoplasm and prominent nucleoli (Diagn Cytopathol 2005;33:116)

Positive stains

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● CD68; variable desmin (40-50%), EMA (40%), CD99 (45%), actin (14%)

Negative stains

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● Factor VIII, CD34, keratin

Molecular / cytogenetics

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● Usually t(12:16)(q13:p11) [ATF1-FUS] or t(12:22)(q13:q12) [ATF1-EWSR1], which is also present in GI clear cell sarcoma

● Also EWSR1-CREB1 (Genes Chromosomes Cancer 2007;46:1051, Clin Cancer Res 2007;13:7322)

● Rarely t(2;22)(q33;q12.2) with EWSR gene rearrangement by FISH (Pediatr Dev Pathol 2009;12:143)

Molecular images

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FISH                                                                        t(12;16) karyotype                              Diagram

Differential diagnosis

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● Aneursymal variant of benign fibrous histiocytoma - no thick pseudocapsule, no inflammatory cells, no significant pleomorphism

● Malignant fibrous histiocytoma

Additional references

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● Archives 2008;132:273, Hum Path 1999;30:1336, Atlas of Genetics and Cytogenetics, Stanford University

End of Skin / Soft Tissue Tumors > Angiomatoid fibrous histiocytoma

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