RESUMEN
INTRODUCTION: Gastrointestinal stromal tumors (GISTs) represent a unique subset of neoplasms within the digestive tract. They can manifest in various organs throughout the digestive tract, ranging from the oral cavity to the anus, with a predilection for the stomach and small intestine. A distinct subtype of GISTs, known as Extra-gastrointestinal stromal tumors (EGISTs), originate outside the typical GIST organs such as the mesentery, retroperitoneum, and occasionally the omentum. EGISTs are relatively rare, accounting for <5 % of all GIST cases. PRESENTATION OF CASE: We present the case of a 30-year-old female patient who presented with an upper abdominal mass associated with anorexia, fever, and weakness. Radiographic imaging revealed a cystic mass beneath the left hypochondrium. Exploratory laparoscopy confirmed the presence of an isolated mass adherent to the gastrocolic ligament and greater omentum. Histopathological examination confirmed GIST, characterized by spindle-shaped cells with DOG1 and CD117/C-kit expression. The patient underwent successful tumor resection and was discharged home with postoperative imatinib therapy. Follow-up at 14 months showed no recurrence. DISCUSSION: The rarity of Gastrointestinal Stromal Tumors (GISTs) in the Greater Omentum highlights diagnostic challenges and underscores the need for further research. Immunohistochemical analysis aids in diagnosis, with Ki-67 staining indicating a high-risk classification. Surgery remains the primary treatment, with potential adjuvant therapy utilizing Imatinib mesylate. CONCLUSION: Our case underscores the rare occurrence of GIST in the Greater Omentum. Despite their infrequency, EGISTs should be considered in intra-abdominal masses, emphasizing accurate diagnosis for appropriate management and the need for further research.