BackgroundIn Japan, the prevalence of synchronous multiple intramucosal gastric carcinoma is reported to be 5–15%. Here is a case of a synchronous small gastric carcinoma fulfilling the definite indication and curative criteria for endoscopic submucosal dissection with multiple lymph node metastases.Case presentationA Japanese woman in her fifties with a history of endoscopic resection for mucosal poorly differentiated adenocarcinoma was evaluated, with the UICC TNM classification stage being cT1aN0M0 cStageIA. She had undergone total gastrectomy with D1 + lymph node dissection. Histopathological examination revealed 16 individual sporadic lesions in the gastric body, with maximum diameter 3 mm and localization in the lamina propria. Twenty-seven nodes were resected, and metastasis of the carcinoma was revealed in 24 nodes.ConclusionsUndifferentiated intramucosal gastric cancer has a relatively high probability of lymph node metastasis; however, synchronous early lesions are often overlooked. Frequent follow-up examinations may increase the detection of multiple gastric cancers.