Pseudomembranous Colitis: Not Always Caused by Clostridium difficile

Abstract

Although classically pseudomembranous colitis is caused by Clostridium difficile, it can result from several etiologies. Certain medications, chemical injury, collagenous colitis, inflammatory bowel disease, ischemia, and other infectious pathogens can reportedly cause mucosal injury and subsequent pseudomembrane formation. We present the case of a middle-aged woman with vascular disease who was incorrectly diagnosed with refractory C. difficile infection due to the presence of pseudomembranes. Further imaging, endoscopy, and careful histopathology review revealed chronic ischemia as the cause of her pseudomembranous colitis and diarrhea. This case highlights the need for gastroenterologists to consider non-C. difficile etiologies when diagnosing pseudomembranous colitis.

Figure 1

CT of the abdomen/pelvis showing mild wall thickening and an ahaustral appearance of the distal colon with pericolonic fat stranding consistent with colitis.

Figure 2

Images from repeat flexible sigmoidoscopy showing (a) erythematous, friable, and ulcerated mucosa in the rectum and (b) edematous and ulcerated mucosa with decreased vascular pattern in the sigmoid colon.

Figure 3

Photomicrographs of rectosigmoid mucosal biopsies demonstrating (a) an ulcer bed with loss of epithelium and extensive granulation tissue and (b) chronic ischemic colitis with architectural distortion, crypt atrophy, and hyalinization of the lamina propria (H&E stain, 20x).