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A 66-year-old male is referred for further evaluation of leukocytosis. Patient reports fatigue and left upper quadrant discomfort for several months. Physical examination reveals no lymphadenopathy but uncovers massive splenomegaly. Laboratory evalua tion shows leukocyte count 62,800/ ,uL. hemoglobin 6.2 g/dl. and platelet count 1 LJ2 .000/ ,uL. Flow cytometry shows increased population of cells expressing CD 11 c. CD20. and CD1 03. and lacking expression of CD25. CD123. TRAP. and Annexin A 1. Peripheral smear is shown below.
What is the most likely diagnosis?
- Chronic lymphocytic leukemia (CLL)
- Mantle cell lymphoma (MCL)
- Hairy cell leukemia variant (vHCL)
- Follicular lymphoma
- Splenic marginal zone lymphoma
Medicine
C. Peripheral slide demonstrates the presence oflarge lymphocytes with irregular cytoplas mic projections and prominent nucleoli. Flow cytometry reveals expression of several markers charac teristic ofHCL, including CD 11c, CD20, and CD 103. Negativity for CD25, CD 123, TRAP, and Annexin A1 in addition to easily obtainable bone marrow aspirate differentiates the classical and variant forms of HCL. The variant form of HCL tends to present with leukocytosis, rather than with pancytopenia, as seen in the classical form. The nucleoli are classically absent in the classic form as compared to prominent in the variant form of HCL. Overexpression of Annexin A1 gene distinguishes the two forms ofHCL as well as differentiating classical HCL from other forms oflymphomas. Treatment regi mens used for the classical form of HCL appear to be less effective when applied to the variant form. Data suggest that monoclonal antibodies have superior outcomes as compared to purine analogue regimens used for classical HCL (Blood. 2009;114(21):4687, Blood. 2010;115(1):21, Lancet. 2004;363(9424):1869, Cancer Treat Rev. 2006;32(5):365, Cancer Treat Rev. 2011;37(1):3).
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