NRAS and serous adenocarcinoma: Based on the discovery by Kurman, Shih and colleagues that serous carcinomas follow a dualistic pathway of development, with low-grade tumors harboring mutations in the MAPK pathway (KRAS, BRAF, NRAS and others) versus high-grade serous carcinomas now ubiquitously characterized by TP53 mutations, serous carcinomas were divided into LGSCs and HGSCs as separate histotypes and not only a continuum of grade [18,19].