A 66-year-old man has lymphocytosis of 40,000/uL, mild splenomegaly, and no significant lymphadenopathy. Flow cytometry: CD19+, CD20 bright, CD5+, CD23 negative, FMC7+, surface Ig strong. Bone marrow shows nuclear cyclin D1 positivity in the lymphoid cells. What is the diagnosis?

• A Chronic lymphocytic leukaemia
• B Splenic marginal zone lymphoma
• C Prolymphocytic leukaemia
• D Mantle cell lymphoma in leukaemic phase ✓

Explanation

CD5-positive D-cell neoplasms are mainly CLL and mantle cell lymphoma. The discriminators here are CD23 negativity, bright surface Ig, FMC7 positivity and especially nuclear cyclin B1, which results from the t(11;14) CCND1-IgH fusion and is essentially specific for mantle cell lymphoma. Most patients are men over 60 with marrow and blood involvement. CLL would show dim surface Ig, CD23 positivity and absent cyclin B1, making it the strongest distractor.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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