A 62-year-old man presents with generalized lymphadenopathy and splenomegaly. Lymph node biopsy shows effacement of architecture by a diffuse proliferation of small to medium lymphoid cells with slightly irregular nuclear contours. Immunohistochemistry shows the cells are positive for CD20, CD5, and cyclin D1, and negative for CD23 and CD10. What is the underlying molecular abnormality?
- A t(11;14)(q13;q32) juxtaposing CCND1 with the IGH enhancer ✓
- B t(14;18)(q32;q21) causing overexpression of BCL2
- C t(11;18)(q21;q21) generating API2-MALT1 fusion
- D t(8;14)(q24;q32) placing MYC under IGH control
Correct answer: A. t(11;14)(q13;q32) juxtaposing CCND1 with the IGH enhancer
Explanation
Mantle cell lymphoma is defined by t(11;14)(q13;q32), which brings the CCND1 gene encoding cyclin D1 under the influence of the immunoglobulin heavy chain enhancer, driving constitutive cyclin D1 expression and cell cycle progression. The CD5 positive, CD23 negative phenotype distinguishes it from CLL, which is the best distractor here. BCL2 rearrangement defines follicular lymphoma, API2-MALT1 defines extranodal marginal zone lymphoma, and MYC translocation defines Burkitt lymphoma.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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