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BDS4 Radiology > Odontogenic Tumours > Flashcards

Odontogenic Tumours Flashcards

1
Q

What are odontogenic tumours

A
  • rare
  • benign
  • often asymptomatic
  • arise in bone of the jaws
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2
Q

What are the 3 groups that odontogenic tumours can be classified into

A
  • epithelial
  • mesenchymal
  • mixed
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3
Q

What are the main 3 epithelial tumours

A

 Ameloblastoma
 Adenomatoid odontogenic tumour
 Calcifying epithelial odontogenic tumour

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4
Q

What is the main mesenchymal tumour

A

Odontogenic myxoma

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5
Q

What is the main mixed tumour

A

Odontoma (aka odontome)

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6
Q

Why can only mixed tumours have dentine/enamel formation

A

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

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7
Q

What are the odontogenic sources of epithelium

A

rests of mallasez
rests/glands of serres
reduced enamel epithelium

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8
Q

What is the rest of mallasez a remnant of

A

hertwig’s epithelial root sheat

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9
Q

What is herwtig’s epithelial root sheat

A

 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)

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10
Q

What is the rests/glands of Serres a remnant of

A

the dental lamina

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11
Q

What is the dental lamina responsible for

A

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

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12
Q

What is the reduced enamel epithelium a remnant of

A

These are remnants of the enamel organ

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13
Q

What is the reduced enamel epithelium

A

 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

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14
Q

What is the growth pace of ameloblastoma

A

slow

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15
Q

What are the symptoms of ameloblastoma

A

Painless
Can be locally destructive however

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16
Q

How common is ameloblastoma

A

1% of oral and maxfax tumours

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17
Q

What is the most common age for ameloblastoma

A

30-60 yrs old

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18
Q

What is the most common location for ameloblastoma

A

Posterior mandible

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19
Q

What gender is ameloblastoma more common in

A

males

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20
Q

What are the radiological types of ameloblastoma

A

multicystic
unicystic (less common)

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21
Q

What population is unicystic lesions more common in

A

younger px

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22
Q

What are the histological forms of ameloblastoma

A

** follicular
* plexiform
* desmoplastic
First 2 most common

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23
Q

What is the growth pace of adenomatoid odonotgenic tumour

A

slow

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24
Q

What is the classic presentation of adenomatoid odontogenic tumour

A

Classic presentation is unilocular radiolucency with internal calcifications around crown of unerupted maxillary canine

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25
Q

How common is adenomatoid odontogenic tumour

A

3% of odontogenic tumours

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26
Q

What is the most common age for adenomatoid odontogenic tumour

A

10-20 year olds

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27
Q

Where is the most common location for adenomatoid odontogenic tumour

A

Anterior maxilla

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28
Q

What is the most common gender for adenomatoid odontogenic tumour

A

females

29
Q

What is the growth pace for calcifiying epithelial odontogenic tumour (CEOT) aka pindborg

A

slow

30
Q

What are calcifying epithelial odontogenic tumours associated with

A

50% associated with unerupted tooth

31
Q

How common are calcifying epithelial odontogenic tumours

A

1% of odontogenic tumours

32
Q

What age group experience calcifying epithelial odontogenic tumours

A

40-50s

33
Q

Where is the most common location for calcifying epithelial odontogenic tumours

A

posterior mandible

34
Q

Which gender are calcifying epithelial odontogenic tumours most common with

A

males

35
Q

How do the margins of ameloblastoma appear on an xray

A

Well defined

Corticated

Potentially scalloped

36
Q

How do multicystic ameloblastoma appear on an xray

A

Most common is multicystic type which may have thick curved septae producing a ‘soap bubble appearance’

37
Q

How does a unicystic ameloblastoma radiographically appear

A

Less common is unicystic time, it would not have scalloped margins as it is one lesion

38
Q

Are ameloblastomas radiopaque or radiolucent on an xray

A

Primarily radiolucent with exception of the desmoplastic type

Depending on how many septae there are, it can be more radiopaque

39
Q

What is the impact of ameloblastoma on adjacent structures

A

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

40
Q

How does ameloblastoma tend to grow

A

Typically expands in all directions equally

41
Q

How do the margins of adenomatoid odontogenic tumour appear on an xray

A

Well defined

Corticated/sclerotic

42
Q

Are adenomatoid odontogenic tumours usually unilocular or multilocular

A

unilocular

43
Q

Are adenomatoid odontogenic tumours radiopaque or radiolucent

A

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

44
Q

What is the impact of adenomatoid odontogenic tumours on adjacent structures

A

May displace adjacent structures but external roto resorption is rare

45
Q

What are the associations of adenomatoid odontogenic tumours

A

75% associated with an unerupted tooth. Looks similar to a dentigerous cyst but typically it is attached to the CEJ.
It impedes eruption

46
Q

How do the margins of calcifying epithelial odontogenic tumours appear

A

Can be well/poorly defined

47
Q

Are calcifying epithelial odontogenic tumours uni or multilocular

A

Can be multi or unilocular

48
Q

Are calcifying epithelail odontogenic tumours radiolucent or radiopaque

A

Radiolucency often with internal radiopacities (variable)

Can have no, fine or coarse internal septa

49
Q

What are calcifying epithelial odontogenic tumours associated with

A

50% associated with unerupted tooth

50
Q

What are the histological features of a plexiform ameloblastoma

A

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

51
Q

What are the histological features of a follicular ameloblastoma

A

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

52
Q

What is the management of ameloblastoma

A
  • Surgical resection with margin
  • 1cm around pathology is removed due to recurrence being common
  • <1% will transform to malignant ameloblastic carcinoma
53
Q

What are the histological features of AOT

A
  • 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
54
Q

How can you differentiate the dental follicle from the AOT

A
  • 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
55
Q

How does the margins of an odontogenic myxoma appear on an xray

A

o Well defined radiolucency with/without a thin corticated margin

56
Q

Are odontogenic myxomas unilocular or multilocular

A

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

57
Q

What is the growth pattern of odontogenic myxomas

A

o Grows along the bone before it expands buccal lingually

58
Q

Do odontogenic myxomas displace

A

o Initially they will scallop up between the roots rather than displace them, the teeth will eventually be displaced however

59
Q

Describe the histological features of odontogenic myxomas

A
  • 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
60
Q

What is the management of odontogenic myxomas

A
  • 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
61
Q

What is an odontoma technically

A
  • 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
62
Q

How does odontoma appear similarly to teeth

A

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

63
Q

What decade is odontoma most common in

A

2nd

64
Q

What gender is odontomas more common in

A

females

65
Q

What are the two types of odontoma

A

compound
complex

66
Q

What is a complex odontoma

A

 Disorganised mass of dental tissue
 More common in the posterior body of the mandible

67
Q

What is a compound ondontoma

A

 Ordered dental structure
 May appear as mini teeth called denticles
 More common in the anterior maxilla
 More common by 2:1

68
Q

What are the histological features of odontoma

A

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

BDS4 Radiology (8 decks)

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