Abstract

The presence of volcano-shaped pseudomembrane(PM) formations above the inflamed mucosa has been referred to as the unique biopsy criterion of the pseudomembranous colitis, but PM might be lost during the bowel preparation, and such loss leads pathologists to erroneous interpretations of the endoscopic biopsy specimens. The purpose of this paper is to identify the additional diagnostic clue other than PM among various histologic features in pseudomembranous colitis. We reviewed sigmoidoscopic biopsy specimens from 13 cases of antibiotics-associated pseudomembranous colitis which was confirmed to reveal characteristic PM by endoscopy aside from the clinical history of antibiotics administration. The cases were divided into two groups: the presence of PM (n=7) and its absence (n=6). Both groups showed basically identical histology, which included features of glandular distension, epithelial necrosis, crypt abscess, regenerative glands and mucous plug within the necrotic/dilated glands. Mucous plugs within the necrotic/ dilated glands were found in all cases and seemed to be the most characteristic microscopic feature. Ten cases of resected chronic ulcerative colitis in the active stage were compared for a differential diagnosis of crypt abscess-associated mucosal change. None of them revealed necrotic gland with mucous plugs, although crypt abscess formation was common in both conditions. We conclude that presence of mucous plugs in the dilated/necrotic glands is a useful diagnostic clue even though the biopsy specimens fail to demonstrate PM.

• Keywords: Antibiotics-associated;Endoscopy;Pathology;Pseudomembranous colitis;