Primary Gastric Angiosarcoma Presenting as an Asymptomatic Gastric Submucosal Tumor

Primary gastric angiosarcoma is a rare gastric tumor. Previously reported cases are limited and usually symptomatic. Preoperative diagnosis is difficult and should be differentiated from adenocarcinoma or gastrointestinal stromal tumor. We report a 55-year-old man with primary gastric angiosarcoma presenting as an asymptomatic gastric submucosal tumor. Abdominal ultrasonography showed a heteroechogenic tumor with several notably anechoic portions between the stomach and the gallbladder. Computed tomography showed that the tumor originated from the stomach, and upper gastrointestinal endoscopy showed a large gastric submucosal tumor at the lower body. Laparotomy was performed and a purple circumscribed tumor measuring 8.5 × 5.0 × 4.0 cm was found on the serosal aspect of the lower body. The tumor was soft and spongy with areas of hemorrhagic pools on section. Microscopically, the tumor was composed of proliferative neoplastic spindle to epithelioid cells. The neoplastic cells infiltrated and dissected the smooth muscle as vessel-forming architectures. On immunohistochemical study, the tumor cells were positive for CD34. These findings confirmed a diagnosis of primary gastric angiosarcoma. The patient has been well during the 11-month postoperative follow-up.