Odontogenic Tumours Flashcards
What are odontogenic tumours
- rare
- benign
- often asymptomatic
- arise in bone of the jaws
What are the 3 groups that odontogenic tumours can be classified into
- epithelial
- mesenchymal
- mixed
What are the main 3 epithelial tumours
Ameloblastoma
Adenomatoid odontogenic tumour
Calcifying epithelial odontogenic tumour
What is the main mesenchymal tumour
Odontogenic myxoma
What is the main mixed tumour
Odontoma (aka odontome)
Why can only mixed tumours have dentine/enamel formation
This is because of the concept of induction where enamel only starts forming once dentine starts to become laid down therefore we cannot have enamel without the presence of dentine first
Enamel is of epithelial origin whereas dentine is of mesenchymal origin
What are the odontogenic sources of epithelium
rests of mallasez
rests/glands of serres
reduced enamel epithelium
What is the rest of mallasez a remnant of
hertwig’s epithelial root sheat
What is herwtig’s epithelial root sheat
Hertwig’s epithelial root sheath is what defines the root shape
It is a 2 cell layered structure
It induces the formation of root dentine
Once the initial layer of root dentine is formed, hertwig’s epithelial root sheat breaks up so there is no enamel in the root
Remains of HERS persist as ‘Rests of Malassez’
The remaining cells are in the PDL but they are inactive (although still vital)
What is the rests/glands of Serres a remnant of
the dental lamina
What is the dental lamina responsible for
The dental lamina is responsible for tooth germ formation
After tooth formation is ceased, the dental lamina is no longer required and it will breakdown
May have plants of cells remaining within the jaws and these are known as rests of serres
What is the reduced enamel epithelium a remnant of
These are remnants of the enamel organ
What is the reduced enamel epithelium
Reduced enamel epithelium is formed in the protection phase when ameloblasts regress to form a protective layer (reduced enamel epithelium)
Overlying the ameloblast cells is an adjacent layer of cuboidal cells (outer enamel epithelium) which forms the dental lamina
What is the growth pace of ameloblastoma
slow
What are the symptoms of ameloblastoma
Painless
Can be locally destructive however
How common is ameloblastoma
1% of oral and maxfax tumours
What is the most common age for ameloblastoma
30-60 yrs old
What is the most common location for ameloblastoma
Posterior mandible
What gender is ameloblastoma more common in
males
What are the radiological types of ameloblastoma
multicystic
unicystic (less common)
What population is unicystic lesions more common in
younger px
What are the histological forms of ameloblastoma
** follicular
* plexiform
* desmoplastic
First 2 most common
What is the growth pace of adenomatoid odonotgenic tumour
slow
What is the classic presentation of adenomatoid odontogenic tumour
Classic presentation is unilocular radiolucency with internal calcifications around crown of unerupted maxillary canine
How common is adenomatoid odontogenic tumour
3% of odontogenic tumours
What is the most common age for adenomatoid odontogenic tumour
10-20 year olds
Where is the most common location for adenomatoid odontogenic tumour
Anterior maxilla
What is the most common gender for adenomatoid odontogenic tumour
females
What is the growth pace for calcifiying epithelial odontogenic tumour (CEOT) aka pindborg
slow
What are calcifying epithelial odontogenic tumours associated with
50% associated with unerupted tooth
How common are calcifying epithelial odontogenic tumours
1% of odontogenic tumours
What age group experience calcifying epithelial odontogenic tumours
40-50s
Where is the most common location for calcifying epithelial odontogenic tumours
posterior mandible
Which gender are calcifying epithelial odontogenic tumours most common with
males
How do the margins of ameloblastoma appear on an xray
Well defined
Corticated
Potentially scalloped
How do multicystic ameloblastoma appear on an xray
Most common is multicystic type which may have thick curved septae producing a ‘soap bubble appearance’
How does a unicystic ameloblastoma radiographically appear
Less common is unicystic time, it would not have scalloped margins as it is one lesion
Are ameloblastomas radiopaque or radiolucent on an xray
Primarily radiolucent with exception of the desmoplastic type
Depending on how many septae there are, it can be more radiopaque
What is the impact of ameloblastoma on adjacent structures
Displacement of adjacent structures: commonly teeth and the inferior alveolar canal
Thinning of bony cortices – this is a sign of an aggressive lesion
‘Knife edge’ external root resorption – clean cut appearance. Characteristic sign
How does ameloblastoma tend to grow
Typically expands in all directions equally
How do the margins of adenomatoid odontogenic tumour appear on an xray
Well defined
Corticated/sclerotic
Are adenomatoid odontogenic tumours usually unilocular or multilocular
unilocular
Are adenomatoid odontogenic tumours radiopaque or radiolucent
Radiolucent
Majority have internal calcifications/radiopacities and increase as the tumour matures
These internal calcifications and radiopacities can vary in size and they can clump together
What is the impact of adenomatoid odontogenic tumours on adjacent structures
May displace adjacent structures but external roto resorption is rare
What are the associations of adenomatoid odontogenic tumours
75% associated with an unerupted tooth. Looks similar to a dentigerous cyst but typically it is attached to the CEJ.
It impedes eruption
How do the margins of calcifying epithelial odontogenic tumours appear
Can be well/poorly defined
Are calcifying epithelial odontogenic tumours uni or multilocular
Can be multi or unilocular
Are calcifying epithelail odontogenic tumours radiolucent or radiopaque
Radiolucency often with internal radiopacities (variable)
Can have no, fine or coarse internal septa
What are calcifying epithelial odontogenic tumours associated with
50% associated with unerupted tooth
What are the histological features of a plexiform ameloblastoma
o Ameloblast-like cells arranged in stands and inbetween them you may get stellate reticulum lie tissue present
o Stellate reticulum is a group of cells located in the centre of the enamel organ of a developing tooth
o Supporting all of this there is fibrous tissue
o There is no connective tissue capsule
o The cells can grow and infiltrate into jaw bones which is the main reason for the high recurrence
What are the histological features of a follicular ameloblastoma
o Islands present with fibrous tissue background
o Islands are bordered by cells that resemble ameloblasts (columnar cells with a darkly staining nucleus)
o The tissue in the middle is a loose tissue that resembles stellate reticulum of the tooth germ
o Other changes can take place within the ‘stellate’ reticulum like tissue e.g formation of squamous epithelium
What is the management of ameloblastoma
- Surgical resection with margin
- 1cm around pathology is removed due to recurrence being common
- <1% will transform to malignant ameloblastic carcinoma
What are the histological features of AOT
- Sometimes epithelial cells are arranged in a duct like structure or are present in sheaths or presents with a ‘rosette’ appearance (bottom right in the right picture)
- Sometimes a degree of calcification is present which is reflected as specks of radiopacity in the x-ray
- Well developed fibrous tissue capsule surrounding the cells so therefore removal of the tumour is straight forward as there is low recurrence
How can you differentiate the dental follicle from the AOT
- Dental follicle tends to be symmetrical all the way around the crown whereas this is not symmetrical, it bulges out more in the mesial of the canine
How does the margins of an odontogenic myxoma appear on an xray
o Well defined radiolucency with/without a thin corticated margin
Are odontogenic myxomas unilocular or multilocular
o When the lesion is small, it is often unilocular
o However as they get larger, they often become multilocular and have a scalloped margin
o The septae are curled and thin resembling a bubbly appearance/tennis racket appearance
What is the growth pattern of odontogenic myxomas
o Grows along the bone before it expands buccal lingually
Do odontogenic myxomas displace
o Initially they will scallop up between the roots rather than displace them, the teeth will eventually be displaced however
Describe the histological features of odontogenic myxomas
- Made up of myxoid tissue which is a loose type of connective tissue
- Has a gelatinous consistency
- Contains stellate like cells but they are fewer in number
- Sometimes there may be small groups of odontogenic epithelium with myxoid tissue but these cells are inactive
- Mesenchymal in origin
- No fibrous tissue capsule so can infiltrate into adjacent bone and increase risk of recurrence post-removal
What is the management of odontogenic myxomas
- Curettage or resection depending on the size
- High recurrence rate (1 in 4)
- Follow up is important
- The rate of recurrence is lower if the lesion is unilocular
What is an odontoma technically
- It is classed as a tumour by WHO, however technically it is a hamartoma which is defined as a mass of disorganized tissue native to a particular anatomical location
How does odontoma appear similarly to teeth
o Mature to a certain stage (do not grow indefinitely)
o Can be associated with other odontogenic lesions e.g dentigerous cysts
o Surrounded by a dental follicle
o Lie above the IAC
What decade is odontoma most common in
2nd
What gender is odontomas more common in
females
What are the two types of odontoma
compound
complex
What is a complex odontoma
Disorganised mass of dental tissue
More common in the posterior body of the mandible
What is a compound ondontoma
Ordered dental structure
May appear as mini teeth called denticles
More common in the anterior maxilla
More common by 2:1
What are the histological features of odontoma
Enamel space is present as enamel is an inorganic structure so during slide preparation, when tissue is placed in a variety of different concentrations, it will dissolve the hard tissue so if enamel is fully calcified, then there won’t be any enamel in the odontoma
