Intercurrent cytomegalovirus colitis in a patient with ulcerative colitis.

Acute intercurrent CMV colitis developed in a patient with UC who was receiving prednisone. CMV infection was suggested by light and electron microscopic study of a rectal biopsy taken during the acute episode and was confirmed by serology done nine months later. The microscopic studies of plastic-embedded tissues demonstrated that infected cells were concentrated in a subendothelial location and were presumably macrophages. Epithelial and endothelial cells were not involved. Steroid therapy and the inflammation and repair process (granulartion tissue) of active UC may have predisposed the present patient to CMV colitis. CMV infection has been reported to be more common in patients with UC than in the general population. Detection of CMV colitis in patients with UC could be of special importance since alteration of immunosuppressive therapy may be indicated.