Clinicians need to understand the differences between TNBC and basal-like breast cancer and the importance of using a hierarchical approach to diagnosis, focusing on thorough evaluation of morphological features, followed by accurate assessment of receptor status (ER, PgR and HER2), with use of surrogate IHC markers or gene expression profiling assays to identify basal-like carcinomas if deemed appropriate. The gene discussed is ERBB2; the disease is breast cancer.