Upon stratifying HER2‐positive cases according to ER status, intra‐tumour mixed architecture heterogeneity and mixed cell membrane pattern, were significantly associated with HER2‐positive/ER‐positive compared to HER2‐positive/ER‐negative tumours (p = 0.007, p < 0.001 and p = 0.007, respectively). Here, ESR1 is linked to neoplasm.