Fit-for-Purpose Immunohistochemical Biomarkers.

There are two aspects of immunohistochemistry (IHC) that are relevant to practicing pathologist: (1) understanding of IHC biomarker panels that are suitable for diagnostic, prognostic and predictive testing, and (2) understanding of IHC quality assurance (QA), which makes sure that the tests in these panels work as they should. The two aspects are closely linked together and call for collaborative approach between pathologists and IHC laboratory technologists as both need to be involved in developing and maintaining IHC biomarkers that are "fit-for-purpose". This article reviews the most current IHC QA concepts that are imminently material to practicing pathologists with emphasis on challenges that are specific to endocrine pathology.