Stromal tumor presents as a large extragastrointestinal mass in the abdominal cavity

SummaryGastrointestinal stromal tumors are nonepithelial neoplasms of the gastrointestinal tract and have been increasingly recognized in recent years. In contrast, stromal tumor outside the gastrointestinal tract is not frequently found. Here, we present a 57-year-old male patient who had abdominal fullness for several months. It was caused by a 23-cm heterogeneous tumor mass that was successfully removed from the left upper abdominal cavity. The tumor adhered tightly to adjacent organs but postoperative histopathological analysis revealed no direct connection to the stomach, liver, pancreas, spleen, or kidneys. Immunohistochemical examination of the tumor revealed proliferative spindle-shaped cells stained positive for CD117 and CD34 and negative for smooth muscle actin and S-100. The patient received regular follow up. A suspected recurrent liver metastatic lesion was noted 2 years later and radiofrequency ablation of the liver tumor was performed followed by oral imatinib treatment. No tumor recurrence was detected at 3 years after radiofrequency ablation. This case reminds us that extragastrointestinal stromal tumors should be considered in the differential diagnosis when a large heterogeneous mass is present in the abdominal cavity. The characteristics of extragastrointestinal stromal tumor are described and the literature is reviewed in this report.