Collagenous colitis with mucosal ulcerations in a patient without nonsteroidal anti-inflammatory drug or lansoprazole use

Chronic watery diarrhea combined with normal-appearing colonic mucosa at endoscopy with abnormal histopathology is classified as microscopic colitis. Microscopic colitis encompasses both collagenous and lymphocytic colitis. A 42-year-old Caucasian woman presented with severe diarrhea for six weeks with loose watery stools every 1-2 h, approximately 15 episodes per day. She denied any melena or significant abdominal pain. She denied nonsteroidal anti-inflammatory drug or lansoprazole use, and was only taking diphenoxylate/atropine for her symptoms. Colonoscopy revealed superficial ulcerations in the distal ascending and transverse colon and scattered ulcerations in the descending and sigmoid colon, with biopsy confirming collagenous colitis. We report a rare case of collagenous colitis accompanied by mucosal ulcerations in the absence of known culprits of mucosal ulcerations, such as nonsteroidal anti-inflammatory drugs or lansoprazole.