8 - Odontogenic tumours Flashcards
What is the split of benign vs malignant odontogenic tumours?
100:1 benign:malignant
How are odontogenic tumours classified?
- based on origin of tissue
- epithelial
- mesenchymal
- mixed
What type of tumour can have enamel and dentine formation?
- mixed
- due concept of induction
- dentine is mesenchymal and enamel is epithelial, but dentine induces enamel production
Give examples of epithelial odontogenic tumours.
- ameloblastoma
- adenomatoid odontogenic tumour
- calcifying epithelial odontogenic tumour
Give examples of mesenchymal odontogenic tumours.
Odontogenic myxoma
Give examples of mixed odontogenic tumours.
Odontoma
What is an ameloblastoma?
- benign epithelial tumour
- locally destructive but slow growing
- painless
- high recurrence
What is the incidence of ameloblastoma?
- 30-50 years
- 80% in posterior mandible
- M>F
What are the radiological types of ameloblastoma?
- multicystic
- unicystic (younger patients, less recurrence)
What are the histological types of ameloblastoma?
- follicular (most common)
- plexiform
- desmoplastic
Describe the radiographic appearance of ameloblastoma.
- well defined, corticated margins
- multicystic are scalloped
- multicystic can have thick septae, giving “soap bubble” appearance
- primarily radiolucent
- can cause displacement of adjacent structures, thinning of bony cortices and knife edge root resorption
What is the management of ameloblastoma?
Surgical resection with margin
What is the risk of malignant transformation of ameloblastoma?
<1%
What is the risk of recurrence of ameloblastoma?
15%
What is adenomatoid odontogenic tumour (AOT)?
- benign epithelial tumour
- 75% associated with unerupted tooth
- impedes eruption of associated tooth
What is the incidence of AOT?
- teenagers
- F>M
- majority in anterior maxilla
Describe the radiographic appearance of AOT.
- unilocular radiolucency with internal calcifications/radiopacities
- well defined, corticated/sclerotic margins that attach apical to CEJ (join PDL)
- may displace adjacent structures but root resorption rare
Describe the histology of AOT.
- distinctive with patchy calcification
- fibrous tissue capsule
- duct like structures
Describe the histology of follicular ameloblastoma.
- islands in fibrous tissue
- cystic changes
- ameloblast like cells
- stellate reticulum like tissue
Describe the histology of plexiform ameloblastoma.
- ameloblast like cells back to back
- stellate reticulum like tissue
- fibrous tissue
What is CEOT?
- calcifying epithelial odontogenic tumour
- benign epithelial tumour
- aka Pindborg tumour
- slow growing but can become large
- 50% associated with unerupted tooth
What is the incidence of CEOT?
- 40s
- M>F
- posterior mandible is most common site
Describe the radiographic appearance of CEOT.
- radiolucency with internal radiopacities
- calcifications of varying sizes
- variable radiographic appearance otherwise
What is an odontogenic myxoma?
- benign mesenchymal tumour
- slow growth along bone before causing notable bucco-lingual expansion
- locally invasive, high recurrence and difficult to remove
Describe the radiographic appearance of odontogenic myxoma.
- well defined radiolucency ± thin corticated margin
- small lesions are unilocular
- large lesions are multilocular with scalloped margins
- “soap bubble” appearance common
- “tennis racket” appearance rare but indicative of odontogenic myxoma
- scallops between teeth in larger lesions can cause displacement of teeth but resorption rare
Describe the histology of odontogenic myxoma.
- loose myxoid tissue with stellate cells
- may contain islands of inactive odontogenic epithelium
- no capsule and is locally invasive
What is the management of odontogenic myxoma?
- curettage
- resection
- follow up important
What is the risk of recurrence of odontogenic myxoma?
25%
What is an odontoma?
- benign mixed tumour (technically hamartoma)
- malformation of dental tissue
- has similarities to teeth (does not grow indefinitely, associated with other odontogenic lesions, surrouned by follicle)
- always above IAN
What is the incidence of odontomas?
- 2/3 of all odontogenic tumours
- teenagers
- F=M
What are the different types of odontoma?
- compound
- complex
What is a compound odontoma?
- ordered dental structures
- appear like mini teeth
- common in anterior maxilla
What is a complex odontoma?
- disorganised mass of dental tissue
- common in posterior body of mandible
