The lymphomas associated with AIDS are quite characteristic, both pathologically and clinically. The vast majority have been of high-grade type, including either small noncleaved lymphoma ("undifferentiated," Burkitt, or Burkitt-like) or immunoblastic lymphoma (immunoblastic sarcoma). Most cases have been of B-lymphocytic origin. Although long-term survival has been reported in occasional patients after combination chemotherapy, median survival has been in the range of 6-12 months.