: Updates focus on high-risk subtypes. Sarcomatoid differentiation is now the primary acknowledged uncommon subtype of Squamous Cell Carcinoma (SCC).
: A dedicated new section covers epithelial tumours derived specifically from the nail bed. WHO Classification of Skin Tumours
: The term "variant" is now reserved strictly for genetic alterations in DNA sequences, rather than being used to describe morphological subtypes. : Updates focus on high-risk subtypes
The (5th Edition, 2025) is the authoritative global standard for diagnosing and categorizing cutaneous neoplasms. Also known as the "Blue Books," this edition shifts toward a more integrated, multidisciplinary approach that combines traditional histopathology with advanced molecular genetics and immunohistochemistry. Key Structural & Conceptual Changes WHO Classification of Skin Tumours