New series! WHO Reporting Systems for Cytopathology Essential for standardizing diagnostic cytopathology practice worldwide, this series will serve as a vehicle for the translation of cytopathology research into practice. The key diagnostic cytopathological features are listed for each tumour type under a defined set of diagnostic categories and described in precise, uniform language. These diagnostic criteria represent the first international consensus and are underpinned by evidence that has been evaluated and debated by experts in the field. Each lesion-specific section includes a dedicated subsection discussing the differential diagnosis of the cytopathological features that can be used throughout the world, including in low-resource settings, followed by a subsection describing the current best-practice application of ancillary testing (including next-generation sequencing) on cytopathology material. The volumes are linked to the linked to the WHO Classification of Tumours series, now in its 5th edition.