Colitis cystica profunda simulating rectal carcinoma.

Localized colitis cystica profunda is a rare, benign disease of the lower gastro-intestinal tract, usually presenting as a rectal mass and characterized microscopically by the presence of mucus-filled cysts in the submucosa. Knowledge of this particular pathological entity is important as it can mimic a well differentiated adenocarcinoma of the rectum and therefore could lead to unnecessary surgical resection. We present a case of colitis cystica profunda misdiagnosed as adenocarcinoma based on their similar clinical picture and histological features.