Challenges of the 5th Edition of the WHO Classification of Thyroid Tumours

<p>Background: The 5th edition of the WHO Classification of Thyroid Tumours introduces significant advancements to improve the diagnosis, classification, and management of thyroid neoplasms. Summary: By integrating morphological, molecular, and clinical features, this edition reflects the evolving understanding of thyroid pathology, reflecting their diverse origins (follicular cell-derived, C-cell-derived, uncertain histogenesis). This classification intends to promote precision medicine, improving diagnostic accuracy, and supports tailored treatment strategies, ultimately optimizing patient care and outcomes. Key Messages: A key update includes the reclassification of low-risk neoplasms, such as the recognition of noninvasive follicular thyroid neoplasm with papillary-like nuclear features, to reduce overtreatment, while papillary thyroid microcarcinoma is no longer a distinct entity. High-grade tumours are now defined by their aggressive features, such as increased mitotic activity and necrosis, highlighting their prognostic importance. Additionally, molecular markers, including BRAF, TERT, RET, and NTRK mutations, play a pivotal role in diagnosis, prognosis, and targeted therapy. </p>