In particular, it has been reported that HER2 overexpression rate progressively increases moving from the poorly cohesive WHO histotype to the mitochondrion-rich adenocarcinoma (MRC), tubular adenocarcinoma, and hepatoid carcinoma (HAS), which showed the highest frequency of HER2 positivity and the worst prognosis [12]. The gene discussed is ERBB2; the disease is hepatoid adenocarcinoma.