Case contributed by Dr Francis Fortin


Pelvic/right iliac fossa pain and fever.

Patient Data

Age: 60 years
Gender: Male

Marked wall thickening of the rectum and distal sigmoid colon with prominent adjacent fat stranding and thickening of fascial planes and peritoneum. Marked vascular recruitment (comb sign). No signs of bowel perforation or abscess. No pneumatosis. Mild free intra-peritoneal fluid.

The mid- and proximal sigmoid colon shows diverticular disease, without signs of complication.


This case illustrates the differing appearance on CT of fat stranding (due to increased water content in connective tissue septations of fat secondary to leaky capillaries brought on by inflammation of any kind), peritoneal and fascial thickening (here the mesorectal fascia and mesosigmoid peritoneal leaflets are markedly thickened) and free fluid (seen notably in the peri-hepatic space).

Case Discussion

Findings are in keeping with proctosigmoiditis, either infectious (statistically more likely) or inflammatory.

Patient went on to have stool cultures, C. difficile antigen testing and several other tests, which were negative (additional stool cultures and parasite search pending).

Colonoscopy was performed, which revealed an edematous and hyperemic rectal and distal sigmoid mucosa diffusely, with hemorrhagic suffusion but without ulceration. The anomalies were seen for the first 35 cm of the endoscopy, with an abrupt cutoff to normal mid-sigmoid. Biopsies showed non-specific inflammation. CMV testing was negative on biopsy specimens. HIV testing was negative.

Patient improved gradually on antibiotics and was scheduled for outpatient follow-up with plans to continue workup to rule out inflammatory bowel disease.

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