Lansoprazole-associated collagenous colitis: a case report.

A 57-year-old man developed chronic, watery diarrhea four weeks after Helicobacter pylori eradication therapy including lansoprazole followed by lansoprazole monotherapy for gastroesophageal reflux disease. Four weeks later the patient was admitted to our hospital. By repeated testing other causes of diarrhea, e. g., infectious diarrhea including Clostridium difficile colitis were excluded. Endoscopy showed a normal colon, histopathology of random biopsies of all sections of the colon demonstrated the characteristic features of collagenous colitis. Withdrawal of lansoprazole lead to prompt and sustained relief. Two months later repeat colonoscopy with biopsies showed no evidence of collagenous colitis. Collagenous colitis as a subtype of microscopic colitis is a rare cause of chronic diarrhea with unknown pathogenesis. The reported case represents an unusual association between medication with the proton pump inhibitor lansoprazole and the development of collagenous colitis suggesting the importance of evaluation of drug use in patients with microscopic colitis.