Pseudomembranous Colitis
Definition
- Colitis secondary to disruption of normal bowel flora
Alternate/Historical Names
- Antibiotic associated pseudomembranous colitis or enterocolitis
- Clindamycin associated pseudomembranous colitis or enterocolitis
Diagnostic Criteria
- Damage is due to toxin A produced by Clostridium difficile in bowel lumen
- Not due to tissue invasion by bacteria
- Damage is centered on the crypts
- Frequently patchy with abrupt involvement of 2-10 or more crypts surrounded by normal crypts
- Entire length of crypt is usually involved
- Affected crypts denuded and distended and appear to erupt into the bowel lumen
- Resembles an erupting volcano
- Lamina propria between involved crypts frequently remains intact
- Pseudomembrane is formed by necrotic epithelial cells, mucus, fibrin and neutrophils
- Neutrophils and fibrin frequently appear linear in pseudomembrane
- Pseudomembrane may not always be identified on biopsy
- Signet ring cells may be seen in rare cases
- Confined to crypts and epithelial surface
- No infiltration into lamina propria
- Cells have small bland nuclei
- Muscularis mucosae, submucosa and muscularis propria are not primarily involved
- Severe cases may result in complete destruction of mucosa leading to toxic megacolon
- Because of patchy involvement, fragments of pseudomembrane may be present without mucosal changes
- This finding should prompt additional sections and/or clinical correlation
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting : November 11, 2009
