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 is a tumor of B-cell lineage. It expresses B-cell specific antigens such as CD19, CD20, and CD22, and B-cell associated antigens such as CD24 and HLA-DR. They also express monotypic surface immunoglobulins (usually IgM). Germinal center markers such as CD10 and BCL-6 are also present. They are negative for CD25, CD30, TdT, and BCL-2.