Two cases of gastrointestinal stromal tumor of the stomach with lymph node metastasis.

Lymph node metastasis from gastrointestinal stromal tumor (GIST) is quite rare. We report two cases of gastric GIST with nodal metastases and results of their mutation analyses. In the first case (78-year-old male), a mass 4.0 cm in size was located at the gastric cardia. Proximal gastrectomy was performed. In the other case (40-year-old female), the gastric tumor was 2.5 cm in size. Computed tomography scan revealed a hepatic metastasis. Imatinib mesylate was administered as primary treatment, at the patient's preference, but the tumors exhibited no response. Wedge resection of the stomach and partial hepatectomy were performed. In both cases, histological examination revealed that the tumors consisted of spindle cells. In the former case, there was an isolated lymph node metastasis at the right cardia. In the latter, three of 5 sampled nodes adjacent to the tumor were positive. In both cases, immunohistochemical analyses showed that primary and metastatic tumors were diffusely positive for CD117 and CD34 and negative for desmin and S100-protein. In the former case, there was a deletion mutation in CD117 exon 11, the most common genotype in GIST. In the latter, there were no detectable mutations in CD117 or platelet-derived growth factor receptor alpha.