A 79-year-old female was referred to our hospital with a submucosal tumor (SMT) in the gastric angle found on plain computed tomography (CT) at another hospital. Esophagogastroduodenoscopy (EGD) showed a submucosal protuberance with small ulcers in the gastric angle, and biopsy showed no malignant findings. Contrast CT showed a 40-mm SMT in the gastric angle. EUS showed the mass as a well-defined 30-mm mass arising from the third layer, with a mixture of hypoechoic and hyperechoic features. EUS-FNA and biopsy showed no malignant findings. Three months later, EGD and contrast CT showed mildly enlarged ulcers. Reexamination of the EUS-FNA and pathology results revealed a small aggregate of epithelial-like cells with a background of mucus, and mucus-rich clear cytoplasm. Suspecting gastric mucinous carcinoma, laparoscopic pyloric gastrectomy was performed, and the pathological diagnosis was mucinous adenocarcinoma, pStage IA (pT1bN0M0).
