S6092 Unmasking Primary Jejunal Angiosarcoma: A Rare and Lethal Small Bowel Tumor

Introduction: Small bowel angiosarcomas are exceedingly rare vascular neoplasms, with fewer than 65 cases reported in the literature. Their nonspecific clinical presentation, deep anatomic location, and aggressive behavior, attributable to their origin from vascular or lymphatic endothelium, often result in delayed diagnosis and early metastatic potential. We report a case of a 48-year-old man who presented with melena and was ultimately diagnosed with biopsy proven primary jejunal angiosarcoma. Case Description/Methods: A 48-year-old man with no prior medical history was admitted following a motor vehicle collision with multiple traumatic injuries, including pelvic fractures, ureteral transection, and retroperitoneal/mesenteric hematomas. During hospitalization, he developed melena and acute anemia requiring transfusion. Computed tomography angiography of abdomen was negative, and esophagogastroduodenoscopy revealed chronic gastritis. Continued bleeding prompted colonoscopy, identifying a rectal ulcer likely from a rectal tube and push enteroscopy revealed a 1.5 cm ulcerated lesion in the proximal jejunum. Surgical resection of a 10 mm jejunal tumor was performed, 57 cm from the ligament of Treitz. Histopathology demonstrated poorly formed vascular channels lined by atypical endothelial cells, strongly positive for CD31 and negative for CD117, consistent with jejunal angiosarcoma. Oncology recommended surveillance imaging every 8-12 weeks for the first 2 years. The patient was briefly lost to follow-up but was recently seen, with repeat imaging showing no recurrence. Discussion: Small bowel angiosarcomas are rare, aggressive vascular tumors, comprising less than 1–2% of all gastrointestinal malignancies. Typically affecting males in the 6th to 7th decade, they often present with nonspecific symptoms such as abdominal pain, melena, or hematochezia, contributing to delayed diagnosis. Risk factors may include prior radiation exposure and genetic predisposition. Metastasis commonly involves the liver, lungs, and peritoneum. Diagnosis relies on imaging (computed tomography, magnetic resonance imaging, positron emission tomography) and histopathology, which shows anaplastic, atypical endothelial cells with anastomosing vasculature. Immunohistochemistry is critical, with CD31, CD34, and von Willebrand factor aiding in diagnosis. Localized tumors with negative margins may undergo surveillance or receive adjuvant paclitaxel due to high recurrence risk. Metastatic cases are managed with systemic chemotherapy. Due to its rarity, a multidisciplinary approach is essential for diagnosis, treatment, and follow-up.