In 1869, Broca proposed a categorization of odontogenic tumours (OTs), using the term odontome to refer to any tumour originating from the dental formative tissues. While preserving Broca's odontome idea, Bland-Sutton and Gabell, James and Payne updated tumour terminology between 1888 and 1914. In their categorization of 1946, Thoma and Goldman eliminated the term "odontome" and classified OTs as tumours of ectodermal, mesodermal, or mixed origin. The hypothesis that reciprocal epithelial-mesenchymal tissue interactions also played a role in the aetiology of OTs served as the foundation for Pindborg and Clausen's categorization (1958). A Collaborating Center for the Histological Classification of Odontogenic Tumours and Allied Lesions (including Jaw Cysts) was created by WHO in 1966 under the direction of Dr. Jens Pindborg. A second edition of the official WHO guidance for classifying OTs and cysts was published in 1992 after the first edition was published in 1971. The WHO Blue Book series' editors decided to publish a volume on head and neck tumours in 2003 that included a chapter on odontogenic tumours and bonerelated lesions. In 2002, Philipsen and Reichart revised the 1992 edition. IARC, Lyon published this book in July 2005.