Inflammatory pseudopolyps are benign, reactive lesions usually arising in chronic inflammatory bowel disease, formed by regenerating mucosa surrounded by ulcerated areas. Their occurrence following acute diverticulitis is exceedingly rare, as diverticular inflammation typically resolves without producing localized polypoid regenerative changes.

We present the case of a 46-year-old male evaluated in the endoscopy unit for follow-up after an episode of acute diverticulitis occurring four months before colonoscopy.

Colonoscopy revealed colonic diverticulosis from the sigmoid colon to the hepatic flexure. A 5-cm sigmoid segment showed luminal narrowing and edematous mucosa, with difficulty advancing the endoscope. Immediately proximal to this segment, an arboriform polypoid lesion measuring approximately 8 mm was identified. The surface showed no features of dysplasia but demonstrated increased vascular pattern. Close inspection of the polyp base revealed glandular elongation. Given the unusual appearance, biopsies were obtained for further evaluation.

Histopathology reported vascular dilation and stroma with abundant collagenous tissue, without adenomatous changes, consistent with an inflammatory lesion. At follow-up, the patient reported persistent but gradually improving abdominal pain since the diverticulitis episode. A second-look colonoscopy was therefore scheduled.

On repeat colonoscopy performed three months later, the previously described sigmoid segment persisted, but the polyp had completely disappeared, leaving a diverticulum containing granulation tissue.

This case represents an uncommon inflammatory pseudopolyp arising after acute diverticulitis, with complete endoscopic resolution on short-term follow-up, highlighting the rarity and transient nature of such reactive postdiverticulitis lesions.