Primary Gastric Leiomyosarcoma: A Case Report

Abstract

Background: Primary gastric leiomyosarcoma constitutes an exceptionally rare and diagnostically elusive mesenchymal neoplasm of the gastrointestinal tract, typically manifesting with nonspecific constitutional and gastrointestinal symptoms that may obfuscate timely clinical recognition and management. Gastric leiomyosarcomas typically originate from the smooth muscle cells of the muscularis propria and are characterised by their aggressive behaviour, with a high potential for local invasion and distant metastasis. Case Presentation: The case of a 45-year-old male with no antecedent comorbid conditions, presenting with chronic melena, intermittent low-grade pyrexia, anorexia, and constitutional fatigue of insidious onset, was presented. Clinical assessment revealed a hemodynamically stable yet anaemic individual. Cross-sectional imaging elucidated a heterogeneously enhancing polypoidal mass lesion in the distal stomach without radiological evidence of disseminated disease. Upper gastrointestinal endoscopy demonstrated a large ulcero-proliferative mass with everted margins, and subsequent histopathological evaluation confirmed a high-grade (Grade 3), primary, unifocal gastric leiomyosarcoma emanating from the submucosal layer along the greater curvature, exhibiting mild necrosis (<10%), stromal haemorrhage, and adjacent mucosal oedema. Immunohistochemistry revealed diffuse immunoreactivity for SMA and h-caldesmon, with a Ki-67 proliferative index of 40–45%, corroborating the diagnosis of leiomyosarcoma. Management and Outcome: The patient underwent a diagnostic laparoscopy followed by open subtotal D2 gastrectomy with Roux-en-Y reconstruction. Histopathologic analysis of resected tissue confirmed negative gastric and duodenal margins, absence of lymphovascular and nodal involvement (pT1pN0, AJCC 8th edition). Postoperative recovery was uneventful; the patient resumed oral intake, ambulated early, and was discharged on postoperative day seven. Adjuvant systemic chemotherapy consisting of five cycles of Ifosfamide and Epirubicin was subsequently initiated. Conclusion: This case underscores the pivotal role of multimodal diagnostic integration—comprising endoscopic visualisation, advanced imaging, and meticulous histopathological examination—in the definitive diagnosis and oncological management of primary gastric leiomyosarcoma. Prompt surgical resection with oncologically sound margins, followed by tailored chemotherapeutic regimens, remains imperative in optimising clinical outcomes in such rare malignancies.