A malignant tumor of the lymphatic system, most commonly affecting children, largely confined to tropical Africa in a zone 15° north and south of the equator. It can arise at various sites, most commonly the facial structures, such as the jaw, and in the abdomen. Complications affecting the nervous system occur in up to 50% of cases. Viruses may possibly play a role in the origin and growth of the tumor, which has been shown to be very sensitive to cytotoxic drug therapy.