Burkitt's Lymphoma : Molecular Genetics
Microscopically, Burkitt's lymphoma consists of diffuse sheets of medium-sized lymphocytes with minimal cellular pleomorphism. The cells have round or oval nuclei, coarse chromatin, multiple punctate nucleoli, and a thin rim of amphophilic cytoplasm. Mitotic activity is brisk and numerous apoptotic cells are present.Burkitt's lymphoma shows translocations involving MYC gene on chromosome 8 at 8q24. The most frequent translocation partner (85% of cases) is IgH locus on chromosome 14 [t(8;14)(q24;q32)]. In a smaller percentage of cases, the rearrangement involves MYC and Ig kappa [t(2;8)(p12;q24)] or lambda [t(8;22)(q24;q11)]. As result of these translocations, the MYC coding sequence is placed adjacent to Ig promoter region which upregulates its expression. This promotes cell cycle progression and inhibits differentiation.