Microscopic colitis: diagnosis and management

Abstract

Microscopic colitis (MC) is a common cause of chronic, non-bloody, watery diarrhoea in older patients. The diagnosis depends on characteristic histological findings. Bile acid malabsorption and autoimmune conditions, including coeliac disease, are more frequently found in patients with MC, but colorectal neoplasia and mortality are not increased. Non-steroidal anti-inflammatory drugs, proton-pump inhibitors, selective serotonin reuptake inhibitors and smoking tobacco confer an increased risk of developing MC. Although a so-called benign disease, which rarely causes serious complications, it does have an impact on the quality of life. Several treatment options exist, but budesonide is the only treatment proven in randomised-controlled trials to be effective and safe for induction and maintenance of remission. This article provides a practical overview for the gastroenterologist looking after patients with MC.

Keywords: chronic diarrhoea; collagenous colitis; lymphocytic colitis; microscopic colitis.

Figure 1

Characteristic colonoscopic findings in microscopic colitis: (A) ‘Cat-scratch colon’: haemorrhagic linear mucosal breaks/tears and (B) cicatricial lesion: fine linear scar-like lesions, possibly the healed remnants of previous cat-scratch type lesions.

Figure 2

Characteristic histology of lymphocytic colitis and collagenous colitis. (A) Lymphocytic colitis with increased intraepithelial lymphocytes (H&E). (B) CD3 immunohistochemistry demonstrates the increased intraepithelial lymphocytes, stained brown. CD3 antigen is specific to T-lymphocytes. (C) Thickened collagen band and loss of surface epithelium in collagenous colitis (Masson’s trichrome). Masson’s trichrome staining protocol stains the subepithelial collagen band blue.