Fatal Sigmoidorectal Intussusception Associated With a Colonic Vascular Lesion Showing AVM-Like Features: A Rare Case.

Intussusception is the telescoping of one bowel segment into another, causing obstruction and ischemia. It is uncommon in adults and is most often associated with an underlying neoplasm. Colonic involvement is less frequent, and arteriovenous malformations (AVMs) represent an unusual etiology, with no previously reported fatal rectosigmoid cases to our knowledge. We describe the case of a 41-year-old man with a medical history of tuberculosis and gastrointestinal disease who suddenly developed severe abdominal pain at home. His condition rapidly deteriorated, and he was transported to the emergency department, where he arrived in cardiac arrest. External examination revealed no signs of trauma. Autopsy showed bilateral pleural effusion and markedly emphysematous lungs. Abdominal examination revealed peritoneal effusion, diffuse bowel wall thickening, and hemorrhagic intraluminal content. A colo-recto-sigmoid intussusception causing near-complete obstruction was identified, with a firm intraluminal mass acting as the lead point. Histopathologic analysis demonstrated a vascular lesion composed of arteries, veins, and capillaries associated with neural hyperplasia, favoring a vascular malformation with AVM-like features. No malignancy was found. This case describes a fatal rectosigmoid intussusception associated with a colonic vascular lesion showing AVM-like features and underscores the importance of considering vascular lesions as potential lead points in adult intussusception.