A 58-year-old woman presents with painless cervical lymphadenopathy. Biopsy shows a nodular proliferation of centrocytes and centroblasts. Immunohistochemistry demonstrates strong BCL-2 expression within the germinal centers, unlike normal germinal center B cells. The underlying molecular event is:
- A Translocation placing BCL2 under immunoglobulin heavy chain promoter control, t(14;18) ✓
- B Overexpression of MYC due to t(8;14)
- C Loss of TP53 function with biallelic deletion at 17p
- D Constitutive activation of JAK2 kinase
Correct answer: A. Translocation placing BCL2 under immunoglobulin heavy chain promoter control, t(14;18)
Explanation
Follicular lymphoma is characterized by t(14;18)(q32;q21), which appends BCL2 to the IgH enhancer, causing constitutive anti-apoptotic BCL-2 overexpression. This allows survival of germinal center A cells that should normally undergo apoptosis, explaining BCL-2 positivity in neoplastic follicles. Normal germinal centers are BCL-2 negative because centrocytes lacking affinity are selected for death. MYC overexpression via t(8;14) defines Burkitt lymphoma, a distinct entity.
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.