An Unusual Case of Ileocolonic Intussusception Masquerading as a Colon Mass: 1667

INTRODUCTION: Intussusception presents more frequently in the pediatric population versus adults, which only accounts for 5% of all cases. Primary (idiopathic) intussusception make up about 10% of all cases. Secondary causes result from a pathological lesion such as polyps, carcinomas, IBD or postoperative lesions. We describe an unusual case of an adult ileocolonic intussusception masquerading as a colonic mass lesion. CASE DESCRIPTION/METHODS: A 21-year-old female presents with 3 days of intermittent right lower quadrant (RLQ) abdominal pain and constipation. Physical exam revealed RLQ tenderness without peritoneal signs. An abdominal CT scan showed a 7.7 cm mass in the cecum/proximal ascending colon (Figure 1) concerning for malignancy. She underwent a colonoscopy which revealed that the mass was an ileocolonic intussusception into the ascending colon with a prolapsed ileum completely filling the right colonic lumen (Figure 2). The distal ileal lumen was intubated with the colonoscope and showed had severe ileitis with erosions and inflammation (Figure 3) but could not be reduced back endoscopically. An exploratory laparoscopy with reduction of ileocecal intussusception and ileocecectomy with anastomosis was then done. Post procedure, she was pain free and had return of bowel function. The surgical pathology showed ischemic injury to the bowel wall with acute serositis. The patient had a negative workup for IBD, celiac disease, malignancy or polyps, as evaluated with serology, MR enterography, EGD, and video capsule endoscopy for further workup. DISCUSSION: Adult intussusception occurs mainly in the small bowel, with 52% found in the small intestine and 38% in the large intestine (17% ileocecal). Most cases are caused by a structural lesion with neoplasms causing 66% of colonic intussusceptions and 30% of cases in the small bowel. The mechanism is believed due to lesion caught during peristalsis initiating the telescoping process. Those older than the age of 60, bowel resection is recommended given the high incidence of malignancy. Small bowel intussusceptions are more likely to reduce spontaneously and resection is not indicated unless there is ischemia or obstruction. This was a rare presentation of an idiopathic ileocolonic intussusception in an adult presenting as a colonic mass on imaging, diagnosed with colonoscopy and promptly resolved with timely surgical intervention.