A 51-year-old man presented to the department of urology for hematuria caused by vesical vasodilation. However, an abdominal contrast-enhanced computed tomography revealed a 35-mm hemispherical gastric submucosal tumor. The patient was then referred to our department, where upper GI endoscopy revealed a 35-mm submucosal tumor in the gastric fornix. Boring biopsy of the gastric tumor performed for diagnostic purpose revealed bleeding at the biopsy site. We attempted to stop the bleeding using clips. However, the bleeding continued for 4 days. We performed hemostatic treatment with argon plasma coagulation, following which the bleeding subsided. Pathological diagnosis of the biopsy specimen revealed gastrointestinal stromal tumor (GIST), and the patient underwent laparoscopic partial gastrectomy. While boring biopsy was useful in diagnosing GIST, it must be performed with care to avoid bleeding.
