Multicentric gastrointestinal stromal tumor of the stomach with wild-type KIT and PDGFRA

Gastrointestinal stromal tumors (GISTs) are usually solitary tumors, mostly situated in the stomach and proximal small intestine. The existence of multiple lesions is thought to be an unusual event in some specific circumstances. Synchronous lesions are commonly viewed as the result of metastatic GIST, especially when the tumors are very different from each other in size and smaller lesions are located on the omentum or peritoneum. Nevertheless, differential diagnosis should include multiple primary sporadic GIST. Here we report a rare sporadic metachronous double GIST of the stomach; both tumors lacked KIT and PDGFRA mutations. The 76-year-old male underwent wedge resection of both gastric tumors and was treated postoperatively with imatinib 400 mg daily. He remained recurrence-free after 20 months of follow-up.