IHC staining is the predominant method of determining HER2 status in breast cancer specimens due to its relative ease to perform with rapid turnaround time and lower cost.19 Although commercially available antibodies have shown wide variation in sensitivity and specificity for formalin-fixed paraffin-embedded (FFPE) tissue samples, in which tissue fixation and pre-treatment have a substantial effect on staining,20,21 a significant improvement of the diagnostic standards in clinical histopathology with quality control measures were able to improve diagnostic performance in clinical practice.22 The gene discussed is ERBB2; the disease is breast cancer.