A Tumor-Like Inverted Meckel's Diverticulum: The Culprit Behind Adult Ileal Intussusception and a Diagnostic Pitfall.

Meckel's diverticulum (MD) is a rare but important differential diagnosis for adult intussusception, particularly when presenting with atypical imaging features, such as a tumor-like mass. Inverted MD with hemorrhagic necrosis is exceedingly rare and may mimic neoplastic lesions. A 65-year-old man presented with acute abdominal pain and distension. He had experienced intermittent abdominal discomfort and a single episode of hematochezia two months prior to presentation. Abdominal computed tomography revealed an ileo-ileal intussusception with a round, high-attenuation mass at the lead point. Surgical resection was performed owing to concerns regarding malignancy. Intraoperatively, an inverted MD with hemorrhagic necrosis was identified. Histology confirmed ectopic gastric mucosa in the MD. The patient's postoperative recovery was uneventful. This case highlights a rare presentation of adult intussusception caused by an inverted necrotic MD mimicking an intraluminal tumor. Recognizing this condition is crucial, especially in patients with unexplained abdominal pain or prior gastrointestinal bleeding. MD should be considered in the differential diagnosis of distal ileal masses to ensure an accurate diagnosis and timely management.