RT Journal Article SR Electronic T1 Immunohistochemistry should undergo robust validation equivalent to that of molecular diagnostics JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 766 OP 770 DO 10.1136/jclinpath-2015-203178 VO 68 IS 10 A1 Kelly Elliott A1 Stephen McQuaid A1 Manuel Salto-Tellez A1 Perry Maxwell YR 2015 UL http://jcp.bmj.com/content/68/10/766.abstract AB Immunohistochemistry (IHC) is a widely available and highly utilised tool in diagnostic histopathology and is used to guide treatment options as well as provide prognostic information. IHC is subjected to qualitative and subjective assessment, which has been criticised for a lack of stringency, while PCR-based molecular diagnostic validations by comparison are regarded as very rigorous. It is essential that IHC tests are validated through evidence-based procedures. With the move to ISO15189 (2012), not just of the accuracy, specificity and reproducibility of each test need to be determined and managed, but also the degree of uncertainty and the delivery of such tests. The recent update to ISO 15189 (2012) states that it is appropriate to consider the potential uncertainty of measurement of the value obtained in the laboratory and how that may impact on prognostic or predictive thresholds. In order to highlight the problems surrounding IHC validity, we reviewed the measurement of Ki67and p53 in the literature. Both of these biomarkers have been incorporated into clinical care by pathology laboratories worldwide. The variation seen appears excessive even when measuring centrally stained slides from the same cases. We therefore propose in this paper to establish the basis on which IHC laboratories can bring the same level of robust validation seen in the molecular pathology laboratories and the principles applied to all routine IHC tests.