What are odontogenic tumours?
Tumours of dental tissues
Can be solid or cystic or mixed
-They can consist of odontogenic epithelium, ectomesenchyme or both.
-They are relatively rare.
What classifies as odontogenic epithelium?
Remnants of dental lamina (Rests of Serres)
Hertwigs root sheath (Malassez)
What classifies as ectomesenchyme?
What is the WHO classification of odontogenic tumours?
-Epithelium without ectomesenchyme
-Epithelium with ectomesenchyme
-Mesenchyme and/or ectomesenchyme +/- epithelium
-Melanotic neuroectodermal tumour infancy
What is an Odontogenic epithelium without ectomesenchyme?
A benign odontogenic tumour. eg:
-Ameloblastoma + variants: Solid, Peripheral, Desmoplastic, Unicystic, Acanthomatous
-Squamous Odontogenic tumour
-Calcifying epithelial odontogenic tumour (CEOT)
-Adenomatoid Odontogenic Tumour
What are the most common odontogenic tumours?
-Adenomatoid odontogenic tumour
-Calcifying odontogenic cyst
What are odontomes?
-The most common type of odontogenic tumour
-Tumour- like lesions consisting of mature calcified dental tissues
-You can get complex or compound odontomes
What is a complex odontome?
Irregular mass of enamel, dentine, cementum and connective tissue
Encapsulated, usually single
Replaces tooth of normal series
Impedes eruption of other teeth
When it erupts can cause secondary infection and pain
What is a compound odontome?
Collection of small tooth-like structures (denticles)
Intercanine region, especially maxilla
Distinction from complex odontome is arbitrary - hybrid variants are common
What is an ameloblastoma?
• Example of epithelial tumour
• Less than 1% of oral tumours
• Mean age 40 years
• Slow growing, locally invasive, painless bone expansion, root resorption
• 80% mandible:
- symphysis (Africans)
• Rare extra-osseous (peripheral) variants
How does an ameloblastoma look on a radiograph?
• Multilocular cystic radiolucency
• +- expansion
• +- root resorption
• Occasionally unilocular/unicystic
• ? dentigerous variants
What is a unicystic ameloblastoma?
Accounts for ~15% of Ameloblastoma. Equal distribution between maxilla and mandible. Usually unilocular associated with the crown of an un erupted tooth peak age 35 years.
80% unerupted tooth
What are the microscopal features of an ameloblastoma?
• Thought to arise from cell rests of Serres
• Ameloblast-like cells surround stellate cells follicular plexiform
What is an ameloblastic fibroma?
• Epithelial tumour with ectomesenchyme
• Most patients below 20 years
• Mandibular molar/premolar region
• Well defined, usually unilocular radiolucency
• Radiopacities in ameloblastic fibro- dentinoma (fibro-odontome)
What is the microscopy of an ameloblastic fibroma?
• Odontogenic epithelium
• Cellular fibroblastic stroma
• With or without inductive changes:
- ameloblastic fibrodentinoma
- ameloblastic fibro-odontome
What is an odontogenic myxoma?
Painless swelling of either jaw
Children or young adults
Unerupted or missing tooth common
- scanty stellate cells
- mucoid stroma +- fibrous tissue
- +-odontogenic rests
- widespread bony infiltration