The WHO Classification of Skin Tumours is the 11th volume in the 4th edition of the WHO series on the classification of human tumours. The series (also known as the Blue Books) has long been regarded by pathologists as the gold standard for the diagnosis of tumours, and it is an indispensable guide for the design of evaluations, clinical trials, and studies involving cancer. These authoritative and concise reference books provide an international standard for anyone involved in cancer research or the care of cancer patients.