Collagenous colitis: histopathology and clinical course.

OBJECTIVES: Collagenous colitis is a chronic diarrheal disease characterized by a normal or near-normal mucosa endoscopically and microscopic inflammation in the lamina propria, surface epithelial injury and a thick subepithelial collagen layer. The symptoms of collagenous colitis vary in duration and intensity, and long periods of remission have been described, but long-term follow-up data are limited. Our goal was to determine the natural clinical history of collagenous colitis and to determine whether there was a relationship between histopathologic changes and course of disease.
METHODS: Cases were identified at the University of Michigan Hospitals using surgical pathology records before 1992. All charts, including medical records from other hospitals, were reviewed, and a telephone interview was conducted with each locatable patient (pt). Biopsy specimens were reviewed by two pathologists for degree of collagen layer thickness, epithelial damage, and inflammation.
RESULTS: There were 31 patients (26 F, 5 M) with a mean age of 66 yr (range 33-83) and a mean duration of symptoms of 5.4 yr at the time of diagnosis. Of the 31 patients, 18 (56%) had some form of arthritis, and 22 (71%) were using NSAIDS regularly at the time of diagnosis. Follow-up interviews were conducted at least 2 yr after diagnosis (mean 3.5 yr, range 2-5 yr) with 27 of 31 patients (3 could not be located, 1 died). Two definable groups of patients were identified: (1) those with either spontaneous or treatment-related symptom resolution (63%), and (2) those with ongoing or intermittent symptoms requiring at least intermittent therapy (37%). There was no significant difference between the two groups with regard to sex, age, associated diseases, and use of medications. Patients with symptom resolution (mean duration 3.1 yr) had been treated with antidiarrheals (6), sulfasalazine (3), discontinuation of NSAIDS (3), reversal of jejunoilial bypass (1), or nothing (4). Those with ongoing symptoms experienced a wide range of symptom severity. Two required only antidiarrheals, but five required or failed steroids, azathioprine, or sandostatin. There was no significant difference in collagen thickness, epithelial damage, and inflammation between the two groups, but Paneth cell metaplasia was seen more often in those with ongoing symptoms. In 24 of 27 patients, diagnostic changes were present in left-sided biopsies.
CONCLUSIONS: In our cohort of patients, 63% had lasting resolution of symptoms after a mean 3.5 yr follow-up. There was a high incidence of arthritis and NSAID use in our population, but there was no relationship between these entities and clinical course or histology. Initial histology, except possibly for Paneth cell metaplasia, did not reliably predict severity or course of disease. Finally, although variable in clinical presentation, treatment-free remissions are common in collagenous colitis.