Molecular Pathology of Primary Central Nervous System Tumors: When and How Immunohistochemical Surrogates Inform...

For a subset of tumors of the central nervous system (CNS), immunohistochemistry (IHC) allows for reaching a histomolecular diagnosis conform or close to the World Health Organization classification without the necessity of performing molecular tests. This article summarizes how IHC can be used for this goal for primary CNS tumors, distinguishing: (1) tumor types that can be diagnosed with certainty by using IHC; (2) tumor types for which a likely diagnosis can be made using IHC, especially so when clinicoradiological features are considered, and (3) tumors for which IHC provides some guidance but is insufficient to suggest a precise, WHO CNS5-conform diagnosis.