Two rare cases of node-positive differentiated gastric cancer despite their infiltration to sm1, their small size, and lack of lymphatic invasion into the submucosal layer.

Early gastric cancer without lymph node metastasis has been reported after the analysis of many cases, and a consensus has been reached about this condition. We report two cases of node-positive differentiated sm1 gastric cancer without lymphatic invasion into the submucosal layer. Case 1 was a 73-year-old man who underwent EMR for 0-IIc early gastric cancer (EGC) on the gastric angle, with a histological diagnosis of tub1. Pathological examination revealed a 0-IIc lesion that was 12 mm in size and sm1 in invasion depth without lymphatic-vascular invasion. However, the infiltration in the submucosal layer was relatively wide. The patient subsequently underwent distal gastrectomy with D2 lymph node dissection. Pathological examination revealed level 2 lymph node metastasis. Case 2 was a 62-year-old woman who underwent ER for a 0-I+IIc-type EGC on the greater curvature of the antrum, with a histological diagnosis of tub1. Pathological examination revealed a 0-I+IIc-type lesion that was 15 mm in size and sm1 in depth. Lymphatic invasions in the muscularis mucosa were found, but none were seen in the submucosal layer. Two years later, follow-up computed tomography (CT) showed a lymph node swelling in the infrapyloric region. Distal gastrectomy with D2 dissection was then performed, and pathological examination revealed level 1 lymph node metastasis. Although the lesions in both patients satisfied the criteria of Gotoda et al. for minimal risk of nodal involvement, lymph node metastasis was observed in these patients. Curative surgery with lymph node dissection is thus required in patients with wide infiltration of the submucosal layer or lymphatic invasion in the muscularis mucosa.