Abstract
The latest (4th) edition of the World Health Organization Classification of Head and Neck tumours has recently been published with a number of significant changes across all tumour sites. In particular, there has been a major attempt to simplify classifications and to use defining criteria which can be used globally in all situations, avoiding wherever possible the use of complex molecular techniques which may not be affordable or widely available. This review summarises the changes in Chapter 8: Odontogenic and maxillofacial bone lesions. The most significant change is the re-introduction of the classification of the odontogenic cysts, restoring this books status as the only text which classifies and defines the full range of lesions of the odontogenic tissues. The consensus group considered carefully the terminology of lesions and were concerned to ensure that the names used properly reflected the best evidence regarding the true nature of specific entities. For this reason, this new edition restores the odontogenic keratocyst and calcifying odontogenic cyst to the classification of odontogenic cysts and rejects the previous terminology (keratocystic odontogenic tumour and calcifying cystic odontogenic tumour) which were intended to suggest that they are true neoplasms. New entities which have been introduced include the sclerosing odontogenic carcinoma and primordial odontogenic tumour. In addition, some previously poorly defined lesions have been removed, including the ameloblastic fibrodentinoma, ameloblastic fibro-odontoma, which are probably developing odontomas, and the odontoameloblastoma, which is not regarded as an entity. Finally, the terminology “cemento” has been restored to cemento-ossifying fibroma and cemento-osseous dysplasias, to properly reflect that they are of odontogenic origin and are found in the tooth-bearing areas of the jaws.
Highlights
Introduction and backgroundThe principle of developing an international standard for the classification of tumours was agreed by the WHO in 1952, but the 1st editions of the International Histological Classification series were not published until after 1967
The classification included a number of bone lesions that have distinctive features when arising in the jaws and which must be distinguished from odontogenic neoplasms
While the Virchows Arch (2018) 472:331–339 authors appeared to recognise that bone lesions are important in the differential diagnosis of lesions of the jaws, they clearly felt that clarity over the odontogenic cysts was not needed
Summary
The principle of developing an international standard for the classification of tumours was agreed by the WHO in 1952, but the 1st editions of the International Histological Classification series were not published until after 1967. The 3rd edition was published in 2005 [3] and excluded the odontogenic cysts but did include bone-related or Btumour-like lesions^. While the Virchows Arch (2018) 472:331–339 authors appeared to recognise that bone lesions are important in the differential diagnosis of lesions of the jaws, they clearly felt that clarity over the odontogenic cysts was not needed. They ignored the fact that there was still ongoing debate regarding the true nature of a number of lesions, which sat at the Bcyst-tumour interface^.
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