A 62-year-old man presents with generalized lymphadenopathy. Node biopsy shows a diffuse proliferation of small to medium atypical lymphoid cells with irregular nuclear contours. Immunohistochemistry: CD20 positive, CD5 positive, CD23 negative, SOX11 positive, cyclin D1 nuclear positivity. What is the underlying molecular event?
- A t(14;18) involving BCL2
- B t(11;14) causing cyclin D1 overexpression ✓
- C t(8;14) involving MYC
- D Trisomy 12
Correct answer: B. t(11;14) causing cyclin D1 overexpression
Explanation
Mantle cell lymphoma is defined by t(11;14)(q13;q32), which places the CCND1 gene next to the immunoglobulin heavy chain enhancer, driving constitutive cyclin D1 expression detectable by IHC. Like CLL it is CD5 positive, but CD23 negativity and cyclin D1 positivity separate it from CLL, where trisomy 12 is a common cytogenetic finding. This distinction matters because mantle cell lymphoma carries a poorer prognosis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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