A case of collagenous colitis diagnosed by colonoscopy after admission for colonic diverticulitis

Abstract

An 83-year-old man presented with right lower abdominal pain and a fever of 37.6°C. Initial blood analysis showed a WBC 10,200 /µl, CRP 1.71 mg/dl, and a slight inflammatory reaction.
Diverticulitis of the ascending colon was diagnosed by abdominal CT. The patient was fasted, given supplementary liquid and antibiotics, and the diverticulitis healed. On the 22nd day of illness, lower gastrointestinal (GI) endoscopy was performed, confirming the diverticulum which occurred frequently in the ascending colon and sigmoid colon. Furthermore, it extended to the descending colon forming a granular mucous membrane, overrunning to an ascending colon under a coating of epithelium. Biopsy specimens from this latter part enabled a diagnosis of collagenous colitis (CC) . Lower GI endoscopy was again performed after cessation of drugs suspected to be the cause, confirming improvement of the mucus colon. This procedure also identified the mucous membrane which was a rough work with a flare, a layer of mucous membrane edema. Collagen fibers with a slightly thickened membrane were seen. If a slight mucous membrane change is expected with administration of a drug, reports of clinical signs and abnormal results from endoscopy should be followed up with a biopsy for diagnostic purposes to assess for the existence of CC.