ERBB2 and neoplasm: All luminal B tumours (11/11 cases, 100 %) were classified as grade 1, while one half of the HER2-overexpression tumours (3/6 cases, 50.0 %) were classified as grade 1 and the other half as grade 3, and 10/21 luminal A cases (47.6 %) were classified as grade 1 and 2 at the same percentage.