Synchronous gastric gastrointestinal stromal tumor and signet-ring cell adenocarcinoma: a case report.

Synchronous tumors of the stomach are uncommon. We present a unique case of gastric synchronous tumors composed of signet-ring cell adenocarcinoma and gastrointestinal stromal tumor (GIST). The two tumors arose at the same site and were sharply juxtaposed without intermingling of morphologically distinct elements. Coincidence probably accounts for this occurrence, even if a common carcinogenic agent had been hypothesized. Preoperative imaging and endoscopic biopsy could lead to the suspicion of synchronous tumors, and an accurate histological identification of both tumors could be achieved by multiple deep endoscopic biopsies. The presence in our case of diffuse carcinomatosis indicates that the signet-ring cell adenocarcinoma had a greater adverse effect on the prognosis than the GIST.