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
Differential Diagnosis
| Chemical / Iatrogenic Colitis |
Antibiotic-associated Pseudomembranous Colitis |
| Diffuse necrosis and sloughing of superficial mucosa |
Frequently patchy involvement of 2-10 crypts with normal surrounding crypts |
| Mucosal microthrombi and hemorrhage |
Not associated with microthrombi or hemorrhage |
| History of endoscopy or introduction of foreign substance |
History of antibiotic therapy |
Both may form a pseudomembrane
| Pseudomembranous Colitis |
Enterohemorrhagic E coli Colitis |
| Endoscopic pseudomembrane |
Pseudomembrane only microscopic |
| Necrotic crypt epithelium erupts into lumen to form pseudomembrane |
Entire upper mucosal layer may slough into lumen to form pseudomembrane |
| Hemorrhage is not prominent |
Prominent hemorrhage and capillary thrombosis |
| C difficile titers elevated |
E coli O157:H7 identified by culture |
| Associated with antibiotic therapy |
Not associated with antibiotic therapy |
| Pseudomembranous Colitis |
Ischemic Colitis |
| Diffuse |
Localized, may form a mass |
| No hyanization of lamina propria |
Hyalinized lamina propria |
| Occasional atrophic crypts |
Atrophic microcrypts common |
| Usually only superficial necrosis |
Necrosis frequently transmural |
| C difficile titer elevated |
C difficile titer negative |
| Associated with antibiotic therapy |
Not associated with antibiotic therapy |
Clinical
- Usually follows treatment with clindamycin, ampicillin or third generation cephalosporins
- Rare cases occur in the absence of antibiotic therapy
- Disruption of normal flora allows overgrowth of Clostridium difficile, and rarely C perfringens
Bibliography
- Noffsinger A, Fenoglio-Preiser CM, Maru D, Gilinisky N. Gastrointestinal Diseases, AFIP Atlas of Nontumor Pathology, First Series, Fascicle 5, 2007.
- Signet-ring cells associated with pseudomembranous colitis. Am J Surg Pathol. 1996 May;20(5):599-602.
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