We report the case of a patient with submucosal tumor (SMT) -like gastric cancer who had been followed up for 5 years. A 67-year-old man who had a SMT-like elevation of about 1 cm in diameter with a mild depression on the lesser curvature of the upper body of the stomach was followed up from 2008. At the examination in 2010, the tumor had enlarged slightly, however, no changes in the morphological characteristics were noted. During the follow-up period, periodic biopsy of the lesion revealed no evidence of carcinoma. Endoscopy carried out in 2013 revealed that the lesion had increased in size to 15 mm and was accompanied by a deep depression in the center. Pathological examination of biopsy specimens obtained from the lesion revealed adenocarcinoma. The urea breath test result for H. pylori infection was positive. Proximal partial gastrectomy was performed. Histological examination of the resected specimen revealed moderately differentiated adenocarcinoma proliferating mainly in the submucosal layer. In cases with small lesions, such as in this patient, it is difficult to make an early diagnosis of SMT-like gastric carcinoma. It is important to perform periodic endoscopic examinations and to be alert to any morphological changes in order to make the diagnosis at an early stage.
