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. Diagnostic criteria, pathological features, and genetic and other associated molecular alterations are described in a disease-oriented manner. This volume updates the existing ICD-O codes and provides new codes for use in epidemiology and cancer registration. It also provides information on clinical features, pathology, genetics, prognosis, and protective factors for each of the tumour types covered. The editors expect that this volume will be of particular interest to pathologists, oncologists, and dermatologists who manage or research skin tumours. Sections are included on all recognized neoplasms (and their variants) of the skin and its adnexae. Since the previous edition, there have been particularly substantial changes to the classification of melanoma, based on the latest information from genetic and molecular studies.