LAUSR

Abstract Introduction: Gastric adenocarcinoma of the fundic gland type (GA-FG) is characterized by a well-differentiated neoplasm. More than 100 cases have been reported, but only a few cases have been described in China. Therefore, its clinicopathological characteristics need to be investigated further. Herein, we report five cases and briefly review the relevant literature. Patient concerns: Five patients, including three women and two men, were identified in the Ningbo Clinical Pathological Diagnosis Center between March 2017 and July 2020. Patients (case 1, case 2, and case 5) underwent gastroscopy due to epigastric pain. Apart from the lesion, others were occasionally discovered on physical examination. Diagnosis: Gastric adenocarcinoma of the fundic gland type (GA-FG). Intervention: Five patients were treated with endoscopic submucosal dissection. Outcomes: Surgical outcomes were good. Esophagogastroduodenoscopy showed a scar with no recurrence, and no postoperative symptoms were observed from 3 to 43 months during the follow-up. Conclusion: We present five cases of well-differentiated tubular adenocarcinoma that mimicked the fundic glands. Cell differentiation by MUC2, MUC5AC, MUC6, pepsinogen-I, and H+/K+-ATPase. Immunohistochemical findings in GA-FG suggested differentiation of the fundic glands. In addition, it has a low proliferation. p53 and Her-2 were negative, and β-catenin was positive in the cytoplasm, indicating that the pathogenesis of this tumor was different from that of traditional intestinal and diffuse gastric carcinomas. In summary, this neoplasm is rare and unusual. To better understand this issue, similar cases should be monitored in the future.