[Collagenous colitis].

Collagenous colitis was first described in 1976 by Lindström as an unusual cause of persistent, watery diarrhea. He noted a large subepithelial band of collagen deposited in the rectum and the colon. Collagenous colitis occurs predominantly in females and is more frequent in the elderly. Radiographic examination of the colon is unremarkable, and the patients show no signs of malabsorption. The diagnosis requires biopsy specimens from the colon, as the disease is focal and less frequently affects the rectum. Biopsies taken only from the rectum cannot exclude the diagnosis. For the time being there is no consensus as to the treatment of the disease. We describe two patients with collagenous colitis successfully treated with prednisolone. The diagnostic importance of total colonoscopy with multiple biopsies in a normal-appearing colon in patients with unexplained chronic watery diarrhea is stressed.