Case Report: Sigmoidorectal intussusception mimicking rectal prolapse-a diagnostic pitfall with surgical implications.

Adult intussusception is a rare condition typically associated with a structural lead point and often requiring surgical management, particularly in colonic forms where malignancy risk is high. Sigmoidorectal intussusception represents an exceptionally uncommon subtype that may clinically mimic rectal prolapse, posing a significant diagnostic challenge. We report the case of a 57-year-old female presenting with an irreducible anorectal mass, initially suggestive of prolapse, in whom computed tomography suggested the diagnosis of sigmoidorectal intussusception, which was subsequently confirmed intraoperatively. The patient underwent emergency surgical resection with primary anastomosis, and histopathology revealed a large tubulovillous adenoma with high-grade dysplasia as the lead point. The postoperative course was uneventful. This case highlights the importance of maintaining a high index of suspicion for intussusception in atypical prolapsing anorectal lesions and underscores the critical role of cross-sectional imaging in differentiating between rectal prolapse and invagination. Timely diagnosis enables appropriate oncologic surgical management and helps avoid potentially inappropriate perineal approaches.