Defecation of a "colon cast" as a rare presentation of acute graft-versus-host disease.

Diffuse involvement of the gastrointestinal tract by graft versus host disease (GVHD) is a common complication of allogeneic hematopoietic stem cell transplant (HSCT). Gastrointestinal GVHD usually presents 3 or more weeks after HSCT and is characterized by profuse diarrhea, anorexia, nausea, vomiting, abdominal pain and gastrointestinal bleeding. We report a case of a 23-year-old male who had undergone allogeneic HSCT and presented with bloody diarrhea on the 90th day post-HSCT. On the fourth day of admission, the patient passed per rectum a 27-cm long pinkish colored fleshy material recognized as a "colon cast". Sigmoidoscopy showed a congested and erythematous rectum with the remaining portion of the "colon cast" attached to the proximal part of the sigmoid colon. A biopsy from the rectal wall was suggestive of grade IV GVHD. The patient was treated with methylprednisolone, cyclosporin and mycophenolate mofetil, with a partial response (diarrhea and abdominal pain improved), but then he developed multiple other medical complications and died after 3 months.