Next-Generation Sequencing in Cytopathology

The practice of diagnostic cytopathology has seen a paradigm shift with the increasing use of cytopathology specimens for molecular testing. Next-generation sequencing (NGS) provides a multiplexed high-Throughput sequencing platform that can simultaneously evaluate multiple genes with high analytic sensitivity using modest amounts of nucleic acid. In patients with advanced-stage malignancy, the cytology specimen may be the only tissue available for diagnosis and molecular testing. Therefore, it is critical for clinical laboratories to validate cytologic specimens for NGS to provide the diagnostic, prognostic, and often predictive information necessary to treat these patients. Several studies have been published outlining the application of NGS in cytology specimens; however, the optimization and validation of these NGS assays in non-formalin-fixed cytologic specimens require diligent laboratory practices and rigorous validation. This chapter provides an overview of NGS testing in cytopathology and outlines some of the key factors that impact NGS in cytologic specimens.