ABSTRACT

Microscopic colitis (MC), is a rare disorder characterised by chronic watery diarrhea, normal endoscopic and histopathological findings and inflammatory changes. MC is one of the most frequent causes of chronic diarrhea. MC is divided into two subgroups; collagenous colitis and lymphocytic colitis. It is still unclear, if these subgroups are the same disease with similar clinical and histopathological characteristics or they are different phenotypes of the same disease. Although etiology is unknown, proposed mechanisms of MC are genetics, autoimmunity, immunological or inflammatory reactions to a luminal antigen (food, microorganisms vs), drugs, bacterial infections and toxins, malabsorption of bile acids and bile, defective absorption of fluid and electrolytes, equilibrium of collagen synthesis and degradation and nitric oxide. The prevalence is higher among adults, especially 6th and 7th decades of life, but increasing in every age group including childhood. MC has nonspecific signs such as chronic, recurrent, watery, nonbloody diarrhea which does not cause dehydratation, abdominal pain, weight loss, fecal incontinence. The laboratory examinations are usually not helpful. The diagnosis is made on the basis of clinical signs and histopathological examinations of biopsy specimens taken from ascendent colon and sigmoid colon. Microscopic colitis caused by drugs and celiac disease should be excluded in the differential diagnosis of the disease. There are not enough well-controlled studies about the treatment of MC. Budesonid is the most studied drug. Anti-diarrheals are usually efficient in mild forms of MC. The long-term prognosis is fairly well.