Abstract
A 43-year old woman visited our hospital complaining of sustained watery diarrhea for four months after receiving lansoprazole therapy for gastroesophageal reflux disease. Physical examination and results from biological and serological investigations were normal. Colonoscopy was performed, and identified longitudinal ulcer scars in the sigmoid colon. A biopsy specimen revealed thickening of the subepithelial collagen bands. In addition, Massonʼs trichrome staining identified subepithelial collagen bands up to 20μm thick. The patient was diagnosed with collagenous colitis on the basis of the histological findings. The collagenous colitis was suspected to be associated with lansoprazole administration. After discontinuation of lansoprazole therapy, the patient’s watery diarrhea ceased and the longitudinal ulcer scars resolved completely within a few days. Thus, the possibility of drug-induced collagenous colitis should be considered as a differential diagnosis in cases of chronic watery diarrhea. Therefore, we recommend questioning such patients regarding their history of drug therapy and ensure that any minor endoscopic findings are not overlooked.
