Macroscopic endoscopic lesions in microscopic collagenous colitis: double case report and review of the literature.

Collagenous colitis is a cause of chronic diarrhea of incompletely elucidated origin, defined by normal laboratory tests, a normal endoscopic appearance of colonic mucosa and specific microscopic inflammatory features on colonic biopsies. We report two cases of macroscopic endoscopic lesions observed in patients suffering from chronic diarrhea, whose biopsies confirmed a diagnosis of collagenous colitis and who were successfully treated in that setting, achieving clinical and endoscopic remissions. By means of a literature review, we summarize what is known about collagenous colitis. We particularly discuss macroscopic findings in that context, drawing attention on the so called "microscopic colitis" in the differential diagnosis of that type of lesions.