S4658 A Rare Case of Small Bowel Leiomyosarcoma Presenting as Ongoing Gastrointestinal Bleeding in a Young Adult Male

Introduction: Small bowel tumors make up only an estimated 2% of all gastrointestinal (GI) tumors and leiomyosarcoma (LMS) account for roughly 0.1%-3% of that fraction. Diagnosis is often delayed due to nonspecific symptoms and patients typically present with late stage disease, obstruction, and perforation. LMS normally occurs in individuals over 50 years old and presentation with GI bleeding is particularly uncommon. Here we present an atypical case of a young, healthy man diagnosed with bleeding small bowel LMS. Case Description/Methods: A 24-year-old man with no past medical history presented with melena in the setting of heavy daily nonsteroidal anti-inflammatory drug use for 1 week to alleviate a toothache. Initial workup revealed hemoglobin of 6.5 g/dL. Esophagogastroduodenoscopy (EGD) was unremarkable. Push enteroscopy revealed a bleeding jejunal diverticulum with surrounding swirling mucosa. Following epinephrine injection and endoscopic clipping, hemostasis was achieved but hemoglobin continued to downtrend. Computed tomography of the abdomen and pelvis showed a 13 cm heterogeneously enhancing pelvic mass originating from the small bowel. Complete surgical resection of the mass and involved jejunum was performed with pathology revealing low grade small bowel LMS. Discussion: LMS is rarely considered in the differential diagnosis of melena in otherwise young, healthy patients. This case illustrates an atypical presentation of small bowel LMS in a young adult without risk factors, with initial misleading findings of a bleeding diverticulum and heavy nonsteroidal anti-inflammatory drug use. This case demonstrates the importance of maintaining a broad differential when initial endoscopic evaluation is unrevealing and highlights value of early broadening of differentials when atypical endoscopic findings are seen. Multidisciplinary collaboration facilitated timely management and favorable outcomes in this case.