When accompanied by invasive lesions, IPNB is known to be associated with conventional tubular adenocarcinoma or mucinous cholangiocarcinoma.22, 23, 24 IPNB is characterized by the intestinal phenotype (mucin2 [MUC2]+/cytokeratin20+), with the carcinogeneses leading to tubular adenocarcinoma and mucinous cholangiocarcinoma associated with increasing MUC1 expression and MUC1‐negativity, respectively.21 The gene discussed is MUC1; the disease is gastric tubular adenocarcinoma.