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Flashcards in Odontogenic tumours Deck (16)
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1

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. 

2

What classifies as odontogenic epithelium?

 Enamel organ

 Remnants of dental lamina (Rests of Serres)

 Hertwigs root sheath (Malassez)

3

What classifies as ectomesenchyme?

 Dental papilla

 Dental follicle

4

What is the WHO classification of odontogenic tumours?

 MALIGNANT:

-Carcinoma 

-Sarcoma

 BENIGN:

-Epithelium without ectomesenchyme

-Epithelium with ectomesenchyme     

-Mesenchyme and/or ectomesenchyme +/- epithelium

-Bone related

 OTHERS:

-Melanotic neuroectodermal tumour infancy

5

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

6

What are the most common odontogenic tumours?

-Odontomes (75%)

-Ameloblastomas (12%)

-Odontogenic myxoma

-Adenomatoid odontogenic tumour

-Ameloblastic fibro-odontoma

-Ameloblastic fibroma

-Calcifying odontogenic cyst

-Odontogenic fibroma

7

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

8

What is a complex odontome?

 Irregular mass of enamel, dentine, cementum and connective tissue

 Encapsulated, usually single

 Molar/premolar region

Clinical complications:

 Replaces tooth of normal series

 Impedes eruption of other teeth

 Expands bone

 Cystic change

 When it erupts can cause secondary infection and pain

9

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

10

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:

- angle

- symphysis (Africans)

• Rare extra-osseous (peripheral) variants

11

How does an ameloblastoma look on a radiograph?

• Multilocular cystic radiolucency

• +- expansion

• +- root resorption

• Occasionally unilocular/unicystic

• ? dentigerous variants

12

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.

 Single cyst

 90% mandible

 80% unerupted tooth

 Luminal

 Intraluminal

 Mural

13

What are the microscopal features of an ameloblastoma?

• Thought to arise from cell rests of Serres

• Ameloblast-like cells surround stellate cells follicular plexiform

14

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)

15

What is the microscopy of an ameloblastic fibroma?

• Odontogenic epithelium

• Cellular fibroblastic stroma

• With or without inductive changes:

- ameloblastic fibrodentinoma

- ameloblastic fibro-odontome

16

What is an odontogenic myxoma?

Mesenchymal tumour

Painless swelling of either jaw

Children or young adults

Soap-bubble radiolucency

Unerupted or missing tooth common

 Microscopy:

- scanty stellate cells

- mucoid stroma +- fibrous tissue

- +-odontogenic rests

- widespread bony infiltration