Unveiling the Enigma of a Colonic Neuroendocrine Tumor Causing Ileocolic Intussusception: A Case Report.

Intussusception in adults is rare and is often associated with a pathologic lead point. While colonic adenocarcinoma is a common cause, well-differentiated colonic neuroendocrine tumors are exceedingly rare. We present a unique case of an ileocolic intussusception due to a distal ascending colonic neuroendocrine tumor, emphasizing the diagnostic challenges and importance of prompt intervention. A 60-year-old male with a previous screening colonoscopy in June of 2022 presented to the Emergency Department with two days of cramping, right upper abdominal pain with associated nausea and two episodes of emesis. A Computed Tomography (CT) scan of the abdomen and pelvis revealed an ileocolic intussusception noted at the level of the hepatic flexure with a lead point. Emergent surgical intervention identified a mass in the distal ascending colon, and a right hemicolectomy with successful side-to-side functional end-to-end anastomosis was performed. Final pathology confirmed a well-differentiated stage III colonic neuroendocrine tumor. After a successful postoperative recovery, a full body Positron Emission Tomography (PET) scan was completed and resulted in no evidence of avid metastatic disease. The patient was placed in cancer remission. Intussusceptions in the adult population are uncommon, and the etiology typically involves a pathologic lead point causing intestinal invagination. In this case, prompt diagnosis and management resulted in successful health outcomes with reduced mortality and morbidity, as untreated intussusception can have devastating results. Given this patient's colonoscopy was approximately one year ago, the probability of a colonic neoplasm acting as the lead point was low. However, identification of the intussusception resulted in a timely and lifesaving emergent right hemicolectomy, as this stage III tumor has a five-year median survival rate of only 50% if left untreated. This case report highlights a rare case of adult ileocolic intussusception involving a lead point at the distal ascending colon identified as an uncommon, well-differentiated stage III neuroendocrine tumor. It showcases the importance of considering intussusception as a diagnosis when evaluating adults with abdominal pain for prompt and adequate intervention, especially when malignant lead points and bowel necrosis are suspected.