Three examples of HER2-positive endometrial cancers (EC) of non-serous histology. (A) H&E of an EC diagnosed as International Federation of Gynecology and Obstetrics (FIGO) grade 2 endometrioid EC (EEC) with (B) aberrant mutant-like p53 immunostaining, (C) strong (in)complete membranous HER2 immunostaining, and HER2 gene amplification by dual in situ hybridization (DISH). (D) H&E of an EC diagnosed as FIGO grade 3 EEC with (E) aberrant mutant-like p53 immunostaining, (F) strong complete membranous HER2 immunostaining, and HER2 gene amplification by DISH. (G) H&E of an EC diagnosed as endometrial clear cell carcinoma with (H) aberrant mutant-like p53 immunostaining, (I) strong complete membranous HER2 immunostaining, and HER2 gene amplification by DISH. All images ×20 objective magnification.