Massive Bleeding from a Small Intestinal Submucosal Tumor-like Arterial Malformation: An Unclassifiable Vascular Lesion Revealed by a Detailed Pathological Evaluation

A 53-year-old woman presented with repeated copious bloody stool. Small bowel capsule endoscopy revealed a submucosal tumor (SMT)-like lesion, with erosion of the surface, in the first third of the small bowel. Balloon-assisted small intestinal endoscopy also revealed a pulsatile SMT-like lesion with an exposed vessel on the surface. This unknown lesion was surgically resected. The histopathological findings of the resected SMT-like lesion showed a dilated artery with thrombosis blockage and recanalization. Since this case could not be classified as any of the small intestinal vascular lesion patterns endoscopically, its classification will require the accumulation of further cases.