A 60-year-old man is found to have lymphocytosis of 40,000/µL on routine CBC. Flow cytometry shows CD5+, CD19+, CD23+, CD10−, FMC7− B cells with weak surface immunoglobulin. Bone marrow shows diffuse lymphocytic infiltration. The smear shows numerous smudge cells. The diagnosis is:
- A Mantle cell lymphoma, leukemic phase
- B Chronic lymphocytic leukemia (CLL) ✓
- C Follicular lymphoma, leukemic phase
- D Splenic marginal zone lymphoma
Correct answer: B. Chronic lymphocytic leukemia (CLL)
Explanation
This presentation is classic CLL: the CD5+/CD19+/CD23+ co-expression with weak surface Ig and negative CD10/FMC7 is the hallmark immunophenotype. Smudge (basket) cells on peripheral smear are characteristic. Mantle cell lymphoma is also CD5+ but CD23−, FMC7+, cyclin D1+. Follicular lymphoma is CD10+, BCL-6+, CD5−. Splenic MZL is CD5−, 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.