Lymphatic invasion in small differentiated-type mucosal gastric cancer.

Endoscopic resection for early gastric cancer is indicated for patients who are at negligible risk of lymph node metastasis. A 71-year-old female underwent endoscopic resection for a 15-mm differentiated-type mucosal gastric tumor, as recommended in the Japanese treatment guidelines. A histological examination revealed lymphatic invasion. Therefore, we performed laparoscopy-assisted distal gastrectomy and D1+ lymph node dissection. A histological examination detected no.3 lymph node metastasis, but no residual cancer cells were observed at the site of the endoscopic resection. This case is rare as lymphatic invasion and lymph node metastasis are highly unusual in small differentiated-type mucosal gastric cancer. Having experienced this case, we consider that en-bloc endoscopic resection of such lesions is extremely important, as it allows precise histological examinations to be performed, which can determine the necessity of additional treatment.