Changes similar to those found in GVHD sometimes occur in immunosuppressed or immunodeficient patients, without transplants or transfusions. The lesion affects any portion of the GI tract but it most often involves the intestines. Patients have various associated diseases including lymphoma, leukemia, combined immune deficiency, severe T-cell deficiency, and Hodgkin disease (625,626). The signs and symptoms resemble those developing following bone marrow transplantation but they occur more rapidly and tend to be associated with a higher fatality rate. A novel T-lymphocyte population has been identified in patients with combined immunodeficiency and features of GVHD (627).