Case report: diffuse gastrointestinal bleeding.

Diffuse gastrointestinal bleeding in an immunodeficient patient is presented. Two hours after in vivo erythrocyte labeling, abnormal activity was observed in the wall of a distended colon. If this abnormal concentration had been luminal, a focal, surgically treatable lesion could not have been excluded. This pattern of hemorrhagic colonic lesions has been described pathologically, but not scintigraphically, in immune deficient patients.