New tumour entities in the 4th edition of the World Health Organization Classification of Head and Neck tumours: odontogenic and maxillofacial bone tumours

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.

Primary intraosseous carcinoma in the parasymphyseal region of mandible: A case report and review

“…The new edition recognizes that though some PIOC may arise from pre-existing cysts, designation as specific subtypes was not necessary nor justified on clinicopathological grounds. [8] The present report describes a case of PIOC of anterior mandible arising de novo in a 56-year-old male patient.…”

Overexpression of Fra‐1, c‐Jun and c‐Fos in odontogenic keratocysts: potential correlation with proliferative and anti‐apoptotic activity

“…We collected 10 OM, 10 DC and 32 OKC samples who underwent surgical curettage at the Hospital of Stomatology, Wuhan University. Diagnosis was determined by two pathologists according to the World Health Organisation (WHO) 2017 classification of head and neck tumours . Representative haematoxylin and eosin (H&E) is shown in Supporting information, Figure .…”

“…Odontogenic keratocysts (OKCs), also known as keratocystic odontogenic tumours, are defined as jaw developmental abnormalities . After being defined as benign tumours for many years, keratocystic odontogenic tumours were reclassified as odontogenic keratocysts by the World Health Organisation (WHO) in 2017 . Compared with other cysts, for example dentigerous cysts (DCs) and radicular cysts, OKCs have distinct clinicopathological features: parakeratinised stratified squamous epithelium, higher locally aggressive behaviour, higher recurrence rates and so forth …”

World Health Organization 4th edition of head and neck tumor classification: insight into the consequential modifications

“…In this editorial, we provide a broad review of the consequential modifications in the newly released 4th edition of the WHO head and neck tumor classification, comment on two selected reviews in this volume of the journal, and succinctly discuss the changes made in the salivary gland tumor chapter [1][2][3]. In general, the new edition represents a streamlined and simplified version from previous editions in an effort to reduce redundancy and to maintain consistency within and between different chapters and topics [4].…”

“…In this volume of the journal, together with this editorial, detailed reviews of the significant changes that have been implemented in the nasal, paranasal and skull base, and odontogenic tumor chapters are thoroughly presented [2,3]. In these reviews, the authors addressed the rationale for accepting new entities and modifying nomenclatures and classification of others.…”