Giant Duodenal Metastatic Gastrointestinal Stromal Tumor (mGIST) in a Young Man.

Gastrointestinal stromal tumors (GISTs) are rare neoplasms affecting the gastrointestinal (GI) tract, primarily in middle-aged and elderly individuals. Originating from interstitial cells of Cajal (ICC), they can develop anywhere in the GI tract, with varying symptoms. Diagnosis involves imaging and tissue acquisition, with surgical excision and tyrosine kinase inhibitors as treatment options. Recurrence rates are high, particularly in larger tumors, which have a significant impact on survival rates. Neoadjuvant therapy may be beneficial in advanced cases. The recent World Health Organization (WHO) classification categorized all GISTs as malignant, emphasizing the importance of prompt diagnosis and management. We are presenting a case of a 24-year-old male who presented with abdominal discomfort and a sensation of pressure while bending forward. The abdominal mass, which was equivalent to the size of a basketball, was disclosed by the physical and radiological examinations. This mass pressurized the surrounding organs and filled the abdominal cavity. During the surgery, we found a well-defined, clearly localized, irregular spherical tumor with two metastases in the greater omentum. The tumor had numerous diverticular expansions of varying diameters. Despite the tumor's substantial size and proximity to adjacent structures and organs, we were able to successfully excise the tumor entirely (R0) and interruptedly suture the duodenum after a partial D4 resection, the tumor's point of origin. The postoperative period was unremarkable. We discharged the patient without any complications and commenced imatinib therapy. During the seven months following the operation, the patient was on adjuvant imatinib therapy and maintained recurrence-free.