How Can IHC Stains Perform So Differently at My Lab vs Yours?

Background: Immunohistochemistry (IHC) began as an extension of special stains (eg, silver, Congo red) used to highlight cell types/substances. In present use, many IHC stains are integral to diagnosis and prognosis. Some biomarker IHC (ex, human epidermal growth factor receptor 2 or HER-2/Neu) requires higher thresholds for validation and quality control. More common non-biomarker IHCs are often underoptimized and undercontrolled, increasing the likelihood of errors. In contrast to anatomic pathology IHC, the immunoassays of clinical pathology (which are based on the same science) undergo rigorous quality checks in a College of American Pathologists (CAP)-accredited laboratory. Objective: To compare IHC to immunoassays and provide an argument that IHC quality controls should be held to a higher standard. Design: Editorial. Results: The “control” standards for IHC are lower than for clinical immunoassay. For IHC, the control can be any concentration (low-high), while for more...