What the eyes cannot see—Limitations of current molecular neuropathological interpretations: A primer

Background: Molecular testing has now been incorporated into the mainstream of neuropathological diagnosis, especially in gliomas. There are multiple molecular markers that determine prognosis, and a few are of therapeutic importance. Currently, a number laboratory techniques are being used to test these molecular markers, with an ever increasing number making the transition from being a research tool to use in day-to-day clinical practice.Objective: The objective of this article is to inform the practicing clinicians of the various molecular markers that may be used in neuropathological practice and to highlight the various laboratory methods that are used and the strengths and drawbacks of each test.Materials and Methods: Using intracranial gliomas as an example of the recent changes, this article highlights the different laboratory methods used for the testing of the most popular molecular markers that are used in clinical practice, namely, 1p19q, IDH, P53, H3K27M, EGFR, ATRX, and TERT and details the strengths and pitfalls of each one of them when compared with the current gold standard.Results: The results of traditional immunohistochemistry are compared to the modern molecular biology techniques, and the differences in interpreting the results are discussed.Conclusion: This article highlights the different ways of molecular testing in neuropathology and their differing interpretations. This knowledge is vital in clinical practice.