Paper I
Question
Aetiopathogenesis of Burkitt’s lymphoma and its morphology
Answer
Aetiopathogenesis
- Burkitt lymphoma is a high-grade B-cell non-Hodgkin lymphoma, strongly associated with Epstein-Barr virus (EBV) infection, particularly in the endemic (African) form
- Characterized by a reciprocal translocation involving the MYC oncogene on chromosome 8, most commonly t(8;14)(q24;q32), juxtaposing MYC next to the immunoglobulin heavy chain gene enhancer, leading to constitutive MYC overexpression
- MYC overexpression drives uncontrolled cell proliferation
- Three clinical variants: endemic (African, jaw/facial bone involvement, near-universal EBV association), sporadic (abdominal presentation, less consistent EBV association), and immunodeficiency-associated (HIV-associated)
Morphology
- Microscopy: Diffuse infiltrate of medium-sized, monomorphic lymphoid cells with round nuclei, multiple small nucleoli, and basophilic cytoplasm containing lipid vacuoles
- “Starry sky” pattern: Characteristic low-power appearance, due to numerous interspersed benign macrophages (containing phagocytosed apoptotic tumour cell debris) scattered against the dark background of densely packed tumour cells, giving a star-like appearance
- Very high proliferation rate (near 100% Ki-67 positivity) reflecting the extremely rapid growth typical of this tumour