Collagenous colitis (CC) is a distinct clinicopathological entity characterized by chronic watery diarrhea and a thickened subepithelial collagen band, and mainly affects middle-aged and elderly women. The etiology of CC is largely unknown ; however, a variety of factors have been implicated including genetic factors, autoimmune diseases, intestinal infections, bile salts and drugs such as proton pump inhibitors, non-steroidal anti-inflammatory analgesics, aspirin, and ticlopidine. Although endoscopy usually reveals only normal or non-specific minimal abnormalities of the colonic mucosa, such as increased capillary growth and multiple longitudinal ulcers called mucosal tears, are occasionally observed. The diagnosis of CC is made based on clinical symptoms and histopathologic features of colonic mucosal biopsies. Improvement may be achieved by cessation of possible causative drugs alone. Antidiarrheal drugs such as loperamide and cholestyramine are recommended as first line treatments, followed by subsequent administration of mesalazine, oral corticosteroids and immunosuppressive drugs in non-respondent cases.
Umeno, J., Matsumoto, T., Nakamura, S., & Iida, M. (2010). Diagnosis and management of collagenous colitis. Gastroenterological Endoscopy, 52(4), 1233–1242. https://doi.org/10.11280/gee.52.1233