Mandible & maxilla
General
WHO classification
Author: Kelly Magliocca, D.D.S., M.P.H.
Editor-in-Chief: Debra L. Zynger, M.D.
Last author update: 2 November 2020
Last staff update: 28 February 2023
Copyright: 2004-2024, PathologyOutlines.com, Inc.
PubMed Search: WHO classification[TIAB] head and neck tumors[TIAB]
Table of Contents
Definition / general | Major updates | WHO (2017) | Microscopic (histologic) images | Additional references | Board review style question #1 | Board review style answer #1Cite this page: Magliocca K. WHO classification. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/mandiblemaxillawhoclassification.html. Accessed November 27th, 2024.
Definition / general
- This classification (WHO 2017) is applicable to tumors that occur throughout the head and neck, including the nasal cavity, paranasal sinuses, skull base, nasopharynx, hypopharynx, larynx, trachea, parapharyngeal space, oral cavity, mobile tongue, oropharynx, salivary glands, neck (including lymph nodes), gnathic maxillofacial bones and ear
Major updates
- New entities:
- Sclerosing odontogenic carcinoma: cytologically bland epithelial malignancy with stromal sclerosis exhibiting aggressive infiltrative growth into muscle and nerve; the infiltrating epithelial component tends to be small single file cords and strands which can be difficult to appreciate on routine sections and is best demonstrated with cytokeratin immunohistochemistry
- Primordial odontogenic tumor: benign tumor composed of an immature variably cellular connective tissue resembling dental papilla or odontogenic ectomesenchyme; the tumor is surfaced by cuboidal to columnar epithelium resembling the inner enamel epithelium of the enamel organ
- Renamed / refined entities:
- Ameloblastic carcinoma: three subtypes of ameloblastic carcinoma listed in WHO 2005 collapsed into a single entity, ameloblastic carcinoma
- Primary intraosseous carcinoma: collapsed the complex 2005 WHO classification of primary intraosseous carcinoma into a single entity, primary intraosseous carcinoma
- Ameloblastoma: classification simplified to three types, ameloblastoma, unicystic ameloblastoma and extraosseous / peripheral types
- Desmoplastic ameloblastoma: reclassified as a histologic subtype of ameloblastoma and not a unique clinicopathologic entity
- Odontogenic fibromas: previously divided into a simple type (epithelium poor) and WHO type (epithelial rich); this distinction was eliminated and odontogenic fibroma is now defined as having variable amounts of inactive looking odontogenic epithelium with or without evidence of calcification
- Cemento-ossifying fibroma: included in the 2017 classification under odontogenic tumors to distinguish it from the juvenile categories of ossifying fibroma
- Keratocystic odontogenic tumor: renamed and reclassified as odontogenic keratocyst; the working group noted evidence currently lacking to justify the continuation of 2005 designation of keratocystic odontogenic tumor
- Calcifying cystic odontogenic tumor: renamed and reclassified as calcifying odontogenic cyst in the absence of justification for classifying the lesion as neoplastic
- Removed entities:
- Odontoameloblastoma: now part of ameloblastoma
- Ameloblastic fibro-odontoma and ameloblastic fibro-dentinoma: now recognized as falling within the spectrum of odontoma, therefore are now classified as odontomas
- Reinstated entities:
- Odontogenic carcinosarcoma included in the 2017 classification of malignant odontogenic tumors due to improved documentation confirming it as distinct
- Notable updates:
- Inclusion of a classification for gnathic epithelial lined cysts is notable; such a classification has not appeared in the WHO since 1992
- Primordial cyst is not used synonymously with odontogenic keratocyst
- Orthokeratinized odontogenic cyst is recognized as distinct from odontogenic keratocyst
- Refined criteria for glandular odontogenic cyst presented
- One nonodontogenic epithelial lined cyst included in the 2017 classification: nasopalatine duct cyst
WHO (2017)
- Odontogenic carcinomas ICD-O
- Ameloblastic carcinoma9270/3
- Primary intraosseous carcinoma, NOS9270/3
- Sclerosing odontogenic carcinoma9270/3
- Clear cell odontogenic carcinoma9341/3
- Ghost cell odontogenic carcinoma9302/3
- Odontogenic carcinosarcoma 8980/3
- Odontogenic sarcomas 9330/3
- Benign epithelial odontogenic tumors ICD-O
- Ameloblastoma9310/0
- Squamous odontogenic tumor9312/0
- Calcifying epithelial odontogenic tumor9340/0
- Adenomatoid odontogenic tumor9300/0
- Benign mixed epithelial and mesenchymal odontogenic tumors ICD-O
- Ameloblastic fibroma9330/0
- Primordial odontogenic tumor
- Odontoma9280/0
- Odontoma, compound type9281/0
- Odontoma, complex type9282/0
- Dentinogenic ghost cell tumor9302/0
- Benign mesenchymal odontogenic tumors ICD-O
- Odontogenic fibroma 9321/0
- Odontogenic myxoma / myxofibroma9320/0
- Cementoblastoma 9273/0
- Cemento-ossifying fibroma 9274/0
- Odontogenic cysts of inflammatory origin ICD-O
- Odontogenic and nonodontogenic developmental cysts ICD-O
- Dentigerous cyst
- Odontogenic keratocyst
- Lateral periodontal cyst and botyroid odontogenic cyst
- Gingival cyst
- Glandular odontogenic cyst
- Calcifying odontogenic cyst9301/0
- Orthokeratinized odontogenic cyst
- Nasopalatine duct cyst
- Malignant maxillofacial bone and cartilage tumors ICD-O
- Chondrosarcoma9220/3
- Chondrosarcoma, grade 19222/1
- Chondrosarcoma, grade 2 / 39220/3
- Mesenchymal chondrosarcoma9240/3
- Osteosarcoma, NOS9180/3
- Low grade central osteosarcoma9187/3
- Chondroblastic osteosarcoma9181/3
- Parosteal osteosarcoma9192/3
- Periosteal osteosarcoma9193/3
- Chondrosarcoma9220/3
- Benign maxillofacial bone and cartilage tumors ICD-O
- Chondroma 9220/0
- Osteoma 9180/0
- Melanotic neuroectodermal tumor of infancy9363/0
- Chondroblastoma 9230/1
- Chondromyxoid fibroma9241/0
- Osteoid osteoma9191/0
- Osteoblastoma9200/0
- Desmoplastic fibroma8823/1
- Fibro-osseous and osteochondromatous lesions ICD-O
- Ossifying fibroma9262/0
- Familial gigantiform cementoma
- Fibrous dysplasia
- Cemento-osseous dysplasia
- Osteochondroma 9210/0
- Giant cell lesions and bone cysts ICD-O
- Central giant cell granuloma
- Peripheral giant cell granuloma
- Cherubism
- Aneurysmal bone cyst 9260/0
- Simple bone cyst
- Hematolymphoid tumors ICD-O
- ICD-O note: The first four digits indicate the specific histological term. The fifth digit after the slash (/) is the behavior code, which indicates whether a tumor is malignant, benign, in situ or uncertain (whether benign or malignant) (WHO: International Classification of Diseases for Oncology, 3rd Edition (ICD-O-3) [Accessed 28 October 2020])
Microscopic (histologic) images
Contributed by Kelly Magliocca, D.D.S., M.P.H.
Adenomatoid odontogenic tumor
Ameloblastic carcinoma
Ameloblastic fibroma
Ameloblastoma
Ameloblastoma, extraosseous / peripheral type
Ameloblastoma, unicystic type
Aneurysmal bone cyst
Calcifying epithelial odontogenic tumor
Calcifying odontogenic cyst
Cemento-osseous dysplasia
Cementoblastoma
Central giant cell granuloma
Cherubism
Chondrosarcoma
Clear cell odontogenic carcinoma
Dentigerous cyst
Dentinogenic ghost cell tumor
Desmoplastic fibroma
Fibrous dysplasia
Gingival cyst
Glandular odontogenic cyst
Inflammatory collateral cysts
Lateral periodontal cyst
Melanotic neuroectodermal tumor of infancy
Nasopalatine duct cyst
Odontogenic fibroma
Odontogenic keratocyst
Odontogenic myxoma / myxofibroma
Odontogenic sarcoma
Odontoma
Orthokeratinized odontogenic cyst
Ossifying fibroma
Osteoma
Osteosarcoma, NOS
Peripheral giant cell granuloma
Primary intraosseous carcinoma, NOS
Primordial odontogenic tumor
Radicular cyst
Simple bone cyst
Solitary plasmacytoma of bone
Squamous odontogenic tumor
Additional references
Board review style question #1
Which new benign entity has been added in the 2017 WHO classification of odontogenic and maxillofacial bone tumors?
- Adenomatoid odontogenic tumor
- Ameloblastic carcinoma
- Primordial odontogenic tumor
- Sclerosing odontogenic carcinoma
Board review style answer #1
C. Primordial odontogenic tumor. Primordial odontogenic tumor is a recently recognized benign odontogenic tumor. Being exceptionally rare in the lung, it was introduced in the 2015 WHO classification of lung tumors. Adenomatoid odontogenic tumor is a benign odontogenic tumor in the WHO classification but is not a new entity in the 2017 edition. Sclerosing odontogenic carcinoma is a new entity in the 2017 WHO but is malignant. Ameloblastic carcinoma is an odontogenic malignancy and is not a new entity in the 2017 edition.
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Reference: WHO Classification of Odontogenic and Maxillofacial Bone Tumors
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Reference: WHO Classification of Odontogenic and Maxillofacial Bone Tumors
