Introduction: Overview of Current Molecular Diagnostic Testing on Cytology Samples

This era of precision medicine has been marked by an accelerating pace of our understanding of the underlying biology that drives a variety of malignancies. This has been enabled by advances in our ability to screen for and detect cancers and obtain cytologic and small biopsy samples for the diagnosis of these malignancies and technological advances in the laboratory medicine sector to identify molecular genetic aberrations that drive these cancers. As the discovery of molecular biomarkers, clinical trials, and therapeutic treatment options continue to evolve, pathologists are being increasingly tasked to leverage cytology and small biopsy samples for diagnostic purposes as well as downstream molecular ancillary testing. This serves to provide guidance and information to their clinical colleagues for prognostication and appropriate clinical management. Molecular testing has been successfully applied to these samples, and this introductory chapter serves to highlight various contexts in which molecular diagnostics and cytology are closely intertwined.