85 Infectious Colitis

Clinical Presentation

A 42-year-old man presents with abdominal cramps, fever, and diarrhea.

Fig. 85.1 (A) An axial contrast-enhanced CT image shows severe bowel wall thickening and enhancement of the ascending colon. (B) Inferior axial scan shows prominent lymph nodes scattered in the mesenteric fat, likely reactive. This finding may favor the infectious etiology of colitis. (C) Axial image through the pelvis shows involvement of the distal large bowel with prominent mesocolic vasculature.

Radiologic Findings

Axial computed tomography (CT) images (Fig. 85.1) of the abdomen obtained after the administration of intravenous contrast show severe bowel wall thickening and pericolonic fat stranding involving the majority of the ascending and the entire transverse colon. Scattered mesenteric lymph nodes are noted.

Diagnosis

Infectious colitis

Differential Diagnosis

Pseudomembranous colitis
Crohn disease
Ulcerative colitis
Ischemic colitis
Radiation colitis
Typhlitis

Discussion

Background

Infectious colitis is caused by a variety of infectious agents and is described in both immunocompetent and immunocompromised or hospitalized patients. The lesions seen in these patients may be either superficial (similar to ulcerative colitis) or transmural (as in Crohn disease), diffuse (cytomegalovirus and Escherichia coli), predominantly right-sided (as seen in colitis caused by Yersinia, Salmonella, amebiasis, and tuberculosis), or mostly left-sided (schistosomiasis, shigellosis, herpes, gonorrhea, syphilis, and lymphogranuloma venereum). Stool analysis, blood culture, and endoscopic biopsy are required for the diagnosis, as there is a considerable overlap in the CT appearance of these colitides.