Book excerpt: The WHO Classification of Tumours of Endocrine Organs is the 10th volume in the 4th Edition of the WHO series on histological and genetic typing of human tumours. This authoritative, concise reference provides an international standard for oncologists and pathologists and will serve as an indispensable guide for use in the design of studies evaluating response to therapy and clinical outcome. Diagnostic criteria, pathological features, and associated genetic alterations are described in a disease-oriented manner. Sections on all recognized neoplasms and their variants include new ICD-O codes, epidemiology, clinical features, pathology, genetics, prognosis, and predictive factors. The book, prepared by 166 authors from 25 countries, contains more than 700 color images and tables and more than 3100 references.