Recent advances in diagnosis and treatment of microscopic colitis.

Microscopic colitis, comprising collagenous colitis and lymphocytic colitis, is a common cause of chronic diarrhea. It is characterized clinically by chronic watery diarrhea and a macroscopically normal colonic mucosa where diagnostic histopathological features are seen on microscopic examination. The annual incidence of each disorder is 4-6/100,000 inhabitants, with a peak incidence in individuals 60-70 years old and a noticeable female predominance in collagenous colitis. The etiology is unknown. Chronic diarrhea, abdominal pain, weight loss, fatigue, and fecal incontinence are common symptoms that impair the health-related quality of life of the patient. There is an association with other autoimmune disorders, such as celiac disease, thyroid disorders, diabetes mellitus, and arthritis. Budesonide is the best-documented treatment, both short-term and long-term. Recurrence of symptoms is common after withdrawal of successful budesonide therapy, and the optimal long-term treatment strategy needs further study. The long-term prognosis is good, and the risk of complications including colon cancer is low. We review the epidemiology, clinical features, diagnosis and treatment of microscopic colitis.