Collagenous colitis: a clinicopathologic correlation.

Collagenous colitis is an unusual cause of chronic, watery diarrhea. To characterize this disease, we reviewed biopsy specimens and the clinical records of 17 patients (9 women and 8 men) with this diagnosis. Intermittent diarrhea with symptom-free intervals lasting years was found in 7 of the 17 patients. Two patients had incapacitating arthralgias, and nine had a mild weight loss. Collagen deposition beneath the surface epithelium formed a continuous layer in 11 but was discontinuous in 5 of the 16 patients who had undergone rectal or colonic biopsies at our institution. The thickness of the collagen band was variable (maximum, 93 microns). The symptoms of the patients did not correlate with the thickness of the collagen layer. Variability in collagen thickness may be related to disease phase and increases the need to obtain multiple biopsy specimens from the sigmoid colon and rectum. The optimal treatment for collagenous colitis is difficult to determine because three of six patients treated only symptomatically in our study had resolution of their diarrhea.