A 62-year-old man presents with generalized lymphadenopathy and splenomegaly. Lymph node biopsy shows monomorphic small lymphocytes with irregular nuclear contours surrounding pale germinal centers. Flow cytometry of blood shows CD5+, CD19+, FMC7+, surface Ig strong, and CD23 negative. Which marker confirms the diagnosis?
- A Terminal deoxynucleotidyl transferase positivity
- B Nuclear cyclin D1 expression ✓
- C Tartrate-resistant acid phosphatase positivity
- D CD10 positivity
Correct answer: B. Nuclear cyclin D1 expression
Explanation
This is mantle cell lymphoma: CD5-positive B cells but CD23-negative, which separates it from CLL where CD23 is positive and surface Ig and FMC7 are dim or absent. The defining event is t(11;14)(q13;q32) juxtaposing CCND1 with the IgH promoter, producing nuclear cyclin D1 overexpression. TdT marks lymphoblasts, TRAP marks hairy cell leukemia, and CD10 marks germinal center-derived tumors such as follicular lymphoma and Burkitt lymphoma.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.