September 2010 – Case of the Month #11

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We thank Angel Fernandez-Flores, M.D., Ph.D., Hospital El Bierzo and Clinica Ponferrada, Ponferrada, Spain, for contributing this case.  To contribute a Case of the Month, follow the guidelines on our Case of the Month page.

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Dermatology Case of the Month #11

Clinical history

An 86-year-old man was diagnosed with atypical chronic myeloid leukemia, with lack of basophilia.  The bone marrow aspirate was suggestive of non-progression to acute leukemia.  Ten months later he presented with more than five cutaneous lesions on his chest and back.  They were red indurated papules, and the largest measured 1 cm in diameter.

Micro images:

Immunohistochemistry:

What is your diagnosis? 

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Diagnosis:

Leukemic vasculitis in the context of leukemia cutis, in a patient with atypical chronic myeloid leukemia.

Discussion:

Chronic myeloid leukemia (CML) is characterized by the t(9;22)(q34;q11) [Philadelphia chromosome], discovered in 1960 by Peter Nowell of the University of Pennsylvania and David Hungerford of the Fox Chase Cancer Center (J Natl Cancer Inst 1960;25:85), or by the fusion transcript of the ABL (#9q34) and BCR (#22q11) genes (Cell 1984;36:93).

Atypical CML is a myelodysplastic / myeloproliferative neoplasm that differs from classic CML by (a) the presence of marked granulocytic and multilineage dysplasia, (b) anemia and thrombocytopenia, (c) the lack of basophilia, and (d) the lack of a BCR-ABL fusion transcript by cytogenetics or RT-PCR (Eur J Haematol 2009;83:292).  Diagnosis requires RT-PCR to rule out a fusion gene, which may be present even with a normal karyotype (Hematol Oncol 2006;24:86).  Atypical CML is also JAK2 negative (Leuk Res 2008;32:1931).

Leukemia cutis is the term used to describe neoplastic infiltration of the skin that arises in patients with systemic leukemias (Am J Clin Pathol 2008;129:130, Praxis 2002; 91:1071).  Occasionally, leukemia cutis precedes systemic leukemia and can be an early diagnostic marker (Clin Exp Dermatol 2004;29;468).  Leukemia cutis tends to indicate an unfavorable prognosis (eMedicine), due to aggressive behavior and short survival (J Am Acad Dermatol 1999;40:966). 

The infiltration of leukemic cells into the dermis or blood vessel walls is termed leukemic vasculitis (J Am Acad Dermatol 2009;61:519, Am J Clin Pathol 1997;107:637).  It is often present in leukemia cutis (Br J Dermatol 2000;143:773).  It is more aggressive than non-vasculitis leukemia cutis, and is associated with a poorer prognosis.  The differential diagnosis includes paraneoplastic vasculitis, which is often caused by antibiotics, cytokines or chemotherapeutic agents (Leuk Lymphoma 2000;40:105).

Nat Pernick, M.D., President
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