MRC1 and neoplasm: Typical POLEmut EC features include: presentation at relatively young age and early stage, high tumour grade with scattered tumour giant cells and a prominent lymphocytic infiltrate.4, 18 Although POLEmut EC are mainly microsatellite‐stable (MSS), unstable cases with MMR‐protein loss have been described.4 Importantly, the occurrence of secondary TP53 mutations have been reported in up to 42% of POLEmut EC, sometimes resulting in subclonal mutant‐like p53 immunohistochemistry.4, 19 Two examples of POLEmut EC are illustrated in Figure 2.