A 65-year-old man has an absolute lymphocyte count of 28,000/µL with small mature-appearing lymphocytes on smear. Flow cytometry shows CD5+, CD19+, CD23+, CD20 (dim), and surface immunoglobulin (dim). The most likely diagnosis is:

• A Mantle cell lymphoma
• B Follicular lymphoma
• C Marginal zone lymphoma
• D Chronic lymphocytic leukemia / small lymphocytic lymphoma ✓

Explanation

CLL/SLL has a characteristic immunophenotype: CD5+, CD19+, CD23+, with dim CD20 and dim surface immunoglobulin. Mantle cell lymphoma is CD5+ but CD23-negative and cyclin D1+. Follicular lymphoma is CD10+, BCL2+, CD5-. Marginal zone lymphoma is CD5- and CD23-.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.