Gastric gastrointestinal stromal tumor with predominant cystic formation diagnosed by endoscopic ultrasound-fine needle aspiration.

A 69-year-old woman who had no symptoms was found to have an intraperitoneal tumor on abdominal ultrasonography in a medical checkup. Thereafter, she was referred to our hospital for a further detailed examination. Contrast-enhanced computed tomography revealed a thin-walled cystic tumor with a diameter of 8 cm and with a hypervascular solid masses in the cystic wall, along with intraperitoneal multiple nodules. The cystic tumor was contiguous with the stomach wall. For solid mass of cystic lesions, endoscopic ultrasound-fine needle aspiration was performed transgastrically with a 25-gauge Franseen needle. Pathologically, the cells in the tumor were spindle shaped with atypical nucleus and were positive for c-kit, CD34, and smooth muscle actin. The tumor was diagnosed as gastrointestinal stromal tumor (GIST). With the diagnosis of gastric GIST with peritoneal dissemination, imatinib chemotherapy was initiated.