Objective: To review the published studies on collagenous and lymphocytic (microscopic) colitis with specific emphasis on clinical features, investigational studies, characteristic histology, possible pathogenesis, disease course, and empirical treatment.
Design: Comprehensive synopsis of the stated objective, prepared for the physician treating patients with collagenous or lymphocytic colitis.
Materials and methods: The medical literature on collagenous and lymphocytic colitis.
Results: Collagenous and lymphocytic colitis are chronic diarrheal illnesses of indeterminate etiology that typically present in the late sixth or early seventh decade of life. These disorders may be distinct entities, although some data support the idea that they are only different manifestations of the same disease. The pathogenesis is unknown but may be on an inflammatory, possibly autoimmune, basis. Physical examination and investigational studies are normal or nonspecific, with fecal leukocytosis the only abnormality found in the majority of patients tested. Association with various gastrointestinal, autoimmune, and rheumatologic conditions has been observed in some patients. Clinical and occasional histologic response has been observed after treatment with anti-inflammatory agents such as 5-aminosalicylate and corticosteroids, and should be used when there is no response to symptomatic therapy.
Conclusions: Collagenous and lymphocytic colitis are uncommon but important causes of chronic diarrhea which are important to diagnose and treat.