EP2000 - A Rare Case of Sigmoid Cancer Mimicking Rectal Prolapse

Purpose/Background: Rectal prolapse affects roughly 0.5% of the population. This condition is six times more common in older women compared to men, and the affected men are typically younger. While no specific etiology for rectal prolapse has been identified, it is thought to be secondary to weakness or dysfunction of the pelvic floor musculature. Colorectal cancer can rarely present as rectal prolapse or sigmoido-rectal intussusception. We present an unusual case of fungating sigmoid mass mimicking rectal prolapse.

Methods/Interventions: 59-year old wheelchair-bound male with chronic spinal stenosis, chronic constipation, and urinary retention presented to our institution with worsening constipation, red-mucoid anal discharge, and mass protruding through the anus. A large, firm, and friable mass was noted to be fungating through the anus with areas of questionable ischemia, which prompted emergent operative intervention. CT scan was consistent with colorectal intussusception. On flexible sigmoidoscopy, the mucosa appeared to be viable, and a large mass was found 25 cm from the anal verge, consistent with mid-sigmoid location was noted to be the lead point. Exploratory laparotomy was performed, intussusception was reduced, and Hartmann's procedure was performed. Given the concern for malignancy, oncological resection with high ligation of the IMA was performed.

Results/Outcomes: Post operative recovery is uneventful. Pathology resulted as moderately differentiated adenocarcinoma with negative margins and low risk features. The tumor was staged IIa pT3N0M0(8th edition AJCC classification) and MMR proficient. Preoperative and follow up CEA levels were within normal range. Interval colonoscopy within 3-6 months was recommended 3-6 months post operatively per NCCN guidelines.

Conclusion/Discussion: Sigmoido-rectal intussusception and rectal prolapse associated with malignancy are rare entities in adult population. A high index of suspicion is required in such unusual cases to rule out pathological lead point such as colorectal malignancy. Misdiagnosis as a benign entity can lead to significant delay in treatment and potential upstaging of the disease.Presentations outside of typical demographics warrant further evaluation such as colonoscopy.

CT abdomen and pelvis showing colorectal intussusception