A 28-year-old man presents with an abdominal mass and ileocecal obstruction. Biopsy shows a high-grade B-cell lymphoma with a starry-sky appearance and cells with squared-off cytoplasmic borders. Ki-67 proliferation index is 99%. FISH shows t(8;14). What is the key oncogenic mechanism?

• A Overexpression of BCL2 leading to inhibition of apoptosis
• B Dysregulated overexpression of the MYC oncogene driving proliferation ✓
• C Overexpression of cyclin D1 driving cell cycle progression from G1 to S phase
• D Activation of the BCR-ABL tyrosine kinase promoting survival signaling

Explanation

t(8;14) juxtaposes MYC (on chromosome 8) next to the immunoglobulin heavy chain enhancer (chromosome 14), causing MYC overexpression and extremely rapid proliferation (Ki-67 near 100%). This is characteristic of Burkitt lymphoma. BCL2 overexpression (A) is seen in follicular lymphoma (t(14;18)) and some DLBCL. Cyclin D1 (C) is the hallmark of mantle cell lymphoma (t(11;14)). BCR-ABL (D) is the Philadelphia chromosome.

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.