Jejunal Leiomyosarcoma Diagnosed via Anterograde Enteroscopy: Case Report of a Rare Presentation of Obstructive Small Bowel Tumor

Primary leiomyosarcoma (LMS) of the small intestine is an uncommon and aggressive malignant tumor. We report the case of a 61-year-old male who presented with postprandial abdominal pain, recurrent vomiting, transfusion-dependent anemia, and significant weight loss. Contrast-enhanced CT showed a large circumferential mass in the proximal jejunum, mesenteric thrombosis, and a hepatic lesion suggestive of metastasis. Anterograde double-balloon enteroscopy revealed an ulceroinfiltrative lesion approximately 40 cm distal to the ligament of Treitz, with friable mucosa and prominent vasculature. Targeted biopsies confirmed a high-grade pleomorphic LMS. The patient underwent segmental enterectomy and partial colectomy; histopathology confirmed high-grade LMS with hepatic metastasis. He recovered uneventfully and was referred for oncologic care. This case highlights the importance of early endoscopic evaluation in patients with obscure anemia and subacute obstructive symptoms. Deep enteroscopy enabled histologic confirmation and timely surgical intervention in a lesion beyond the reach of conventional endoscopy.