The results indicated that the present prometastatic intramucosal gastric cancer with extraordinary LN metastasis did not harbor any common mutations for gastric cancer such as TP53, ARID1A, PIK3CA, CDH1, SMAD4, APC, KRAS, or RHOA or its regulatory molecules, AKAP13 and DLC1. Instead, the present case harbored somatic mutations in the LN metastasis: NBN, p.P6S, and PAX8, p.R49H. Here, PIK3CA is linked to gastric cancer.