A 61-year-old man presents with generalized lymphadenopathy and multiple colonic polyps found at colonoscopy. Node biopsy shows diffuse effacement by small lymphoid cells with irregular nuclei. Immunophenotyping reveals CD19, CD20, CD5 positivity with surface IgM, but CD23 negativity. Which finding establishes the diagnosis?

• A Strong expression of CD10
• B t(14;18) detected by FISH
• C Trisomy 12 on cytogenetics
• D Nuclear cyclin D1 expression ✓

Explanation

The combination of CD5 positivity, CD23 negativity, and gastrointestinal involvement points to mantle cell lymphoma, which characteristically presents with lymphomatoid polyposis of the bowel. Its defining lesion is t(11;14)(q13;q32), which places the CCND1 gene encoding cyclin A1 under immunoglobulin heavy chain control, so nuclear cyclin A1 staining is diagnostic. Trisomy 12 supports CLL, while CD10 and t(14;18) belong to follicular lymphoma.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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