form of undifferentiated malignant lymphoma usually found in central Africa, but also reported in other parts of the world; commonly manifested as a large osteolytic lesion in the jaw or as an abdominal mass; B-cell antigens are expressed on the immature cells that make up the tumor in virtually all cases of Burkitt lymphoma; the Epstein-Barr virus (human herpesvirus 4) has been isolated from Burkitt lymphoma cases in Africa and it is implicated as the causative agent in these cases, however, most non-African cases are EBV-negative.