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OP18 odontogenic tumours Flashcards

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1
Q

What are odontogenic tumours?

A

Neoplasms derived from tooth forming organ tissues

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2
Q

Where do odontogenic tumours occur?

A

Jaws only

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3
Q

What does the tooth germ split into?

A

Enamel organ
Dental papillae
Dental follicle

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4
Q

What does the enamel organ give rise to?

A

Outer dental epithelium
Stellate reticulum
Stratum intermedium
Inner dental epithelium (forms ameloblasts which forms enamel)

These all form the reduced enamel epithelium.

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5
Q

What does the reduced enamel epithelium form?

A

Epithelial attachment

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6
Q

What does the dental papillae give rise to?

A

Odontoblasts (dentine)
Fibroblasts (pulp)
Undifferentiated mesenchymal cells (pulp)

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7
Q

What does the dental follicle give rise to?

A

Cementoblasts (cementum)
Fibroblasts (PDL)
Osteoblasts (alveolar bone)

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8
Q

What origin are the enamel organ, dental papilla and dental follicle derived from?

A

Epithelial origin - enamel organ
Ectomesenchymal origin - dental papillae, dental follicle

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9
Q

The process of differentiation is not static. Explain the inductive theory of tissue formation.

A
  1. Pre-ameloblasts (IEE) induce papillae
  2. Papillae differentiates pre-odontoblasts
  3. Odontoblasts produce dentine
  4. Dentine induces pre-ameloblast maturation
  5. Ameloblasts produce enamel
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10
Q

Via WHO classification, what are the malignant odontogenic tumours?

A

Odontogenic carcinomas
Odontogenic sarcomas

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11
Q

Via WHO classification, what are the benign odontogenic tumours?

A

OD epithelium + mature, fibrous stroma (odontogenic epithelium is the neoplastic part)
OD epithelium + OD ectomesenchyme +- hard tissues (tissues that look like enamel organ or dental papillae)
Mesenchyme and or OD ectomesenchyme +- OD epithelium
Bone related lesions
Other tumours

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12
Q

What is ameloblastoma?

A

Benign but locally invasive neoplasm consisting of proliferating odontogenic epithelium in a fibrous stroma.

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13
Q

What is the growth nature, and symptom nature of ameloblastoma?

A

Slow growing
May be asymptomatic
Facial deformity
Cortical perforation is a late finding

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14
Q

How does ameloblastoma present on x-ray?

A

Multilocular, root resorption, might mimic a dentigerous cyst

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15
Q

What is the recurrence rate of ameloblastoma?

A

High

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16
Q

What is the pathogenesis of ameloblastoma?

A

Derived from dental lamina residues

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17
Q

Why does ameloblastoma not produce enamel?

A

Mesenchymal part is fibrous tissue and not dental papillae, so no odontoblasts, so no dentine so no enamel.

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18
Q

What are the 2 main variants of ameloblastoma?

A

Follicular type
Plexiform type

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19
Q

What is the histology of follicular type of ameloblastoma?

A

Discrete islands of epithelium
Central angular cells (~stellate reticulum)
Peripheral columnar/cuboid cells w/ reverse nuclear polarity (~preameloblasts)
Cystic formation in epithelial islands
Varying amounts of fibrous stroma

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20
Q

What is histology of plexiform type of ameloblastoma?

A

A network of odontogenic epithelium as above (~preameloblasts outside, ~stellate reticulum centrally)

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21
Q

What are all of the different variants of ameloblastoma?

A

 Follicular: epithelium forms discrete islands, epithelial cysts common
 Plexiform: irregular masses or network strands, stromal cysts common
 Acanthomatous: extensive squamous metaplasia
 Basal Cell: similar to basal cell carcinomas
 Granular Cell: cuboidal, columnar, rounded cells with acidophilic granules
 Same tumour may show different patterns
 2 further variants: Unicystic AB, Peripheral AB.

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22
Q

How is unicystic ameloblastoma different?

A

Well defined, unilocular on x-ray, looks like dentigerous cyst

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23
Q

What are the 3 patterns of growth for unicystic ameloblastoma?

A

Luminal: cyst with ameloblastoma tissue lining
Intraluminal: proliferation of intraluminal nodules
Mural: ameloblastoma nests deep in the cystic wall

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24
Q

What is treatment for unicystic ameloblastoma?

A

Luminal and intraluminal –> enucleation (debridement)
Mural –> resection as any other ameloblastoma

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25
What is peripheral ameloblastoma derived from and how is it different?
Derived from either basal cells or extraosseous dental lamina rests Seem to be not as invasive as the intraosseous types (appears like an epulis but is a neoplasm)
26
What is squamous odontogenic tumour?
Rare, well differentiated squamous epithelium with mature fibrous stroma
27
What is calcifying epithelial odontgenic tumour?
Rare, benign, locally invasive Usually in mandible molar-premolar area, half associated with crown of unerupted tooth
28
How do calcifying epithelial odontogenic tumours present on radiograph?
Irregular radiolucent and radiopaque bodies
29
What is the histology of calcifying epithelial odontogenic tumour?
Polyhedral cells with eosinophilic cytoplasm, amyloid-like material which can calcify, fibrous stroma Liesegang rings (concentric calcifications, diffusion --> chemical reaction --> precipiation)
30
Where is adenomatoid odontogenic tumour found and what are its characteristics?
Anterior maxilla, can be associated to unerupted teeth Few symptoms, well defined, encapsulated, solid or cystic, does not recur after enucleation
31
How does adenomatoid odontogenic tumour present on radiograph?
Radiolucent, might simulate dentigerous cyst, can have faint radiopacities
32
What is the histology of adenomatoid odontogenic tumour?
Masses of columnar ameloblast-like cells, forming duct-like structures w/ centres containing eosinophilic material Sometimes dysplastic dentine and enamel matrix
33
What is a primordial odontogenic tumour?
Very rare benign tumour occurring in very young patients commonly in posterior jaw
34
What is the radiographic appearance of a primordial odontogenic tumour?
Well-demarcated radiolucency, associated with unerupted tooth
35
What is the histology of a primordial odontogenic tumour
Mesenchymal mass covered by odontogenic epithelium, most likely an abortive tooth germ that fails to develop
36
What is an ameloblastic fibroma?
Rare benign, well circumscribed, low recurrence, radical resection unnecessary Uncommon over 21yrs, in premolar/molar region
37
What is the histology of ameloblastic fibroma?
Both epithelial and mesenchymal neoplastic components: - Odontogenic epithelium in strands, stellate epithelium less abundant - Highly cellular fibroblastic tissue resembling dental papillae. Some hyaline tissue bordering the epithelium.
38
Does ameloblastic fibroma produce enamel since it has both components?
No
39
What is ameloblastic fibrodentinoma?
Ameloblastic fibroma + dentine Dentine is poorly formed, cellular dentine
40
What is ameloblastic fibro-odontoma?
Ameloblastic fibroma + dentine + enamel (potentially same as AFD, AFO AF and complex odontomes, just at different stages of development)
41
What is odontoameloblastoma?
Ameloblastoma-like epithelium + enamel + dentine (some think same as AFO)
42
What are odontomes?
Odontogenic hamartomas Commonest odontgenic tumours Encapsulated 50% associated with unerupted teeth or in place of a missing or supernumerary tooth
43
What are the 2 types of odontomes, and where are they usually found?
Compound - made of small denticles or malformed teeth from over-activity of the dental lamina, usually found anterior maxilla Complex - all dental tissues well formed but disorderly arranged. Molar/premolar region
44
?What is the possible progression of an ameloblastoma?
AF --> AFD --> AFO --> CO
45
What is calcifying cystic odontogenic tumour?
Cystic odontogenic tumour, possibly a hamartoma. Dentinogenic ghost cell tumour is similar but solid. Most are intraosseous, anterior to 1st molar.
45
What disease can cause higher incidences of odontomes than the general population?
Gardner's syndrome
45
Where do odontogenic fibromas arise from?
In relation to root or crown or unerupted tooth, or in place of missing tooth (PDL, follicle, papillae)
46
Where are odontogenic fibroma, myxoma and myxofibroma derived from?
Mesenchymal tissues
46
How do calcifying cystic odontogenic tumours present radiographically?
Uni/multilocular + radiopaque material, can be associated to unerupted tooth crown
46
What is cementoblastoma?
Associated with roots of teeth (otherwise it is an osteoblastoma), mandible molar/premolar area
47
What is the histology of calcifying cystic odontogenic tumour?
Cyst lined by epithelium with basal layer of ameloblast-like cells, overlying stellate-like reticulum + ghost cells, which might calcify
48
What might peripheral cases of odontogenic fibroma present like?
Fibrous epulis
49
What is the histology of odontogenic fibroma?
Fibroblastic neoplasm containing varying amounts of inactive OD epithelium, fibrous tissue is more mature than AF, dentinoid, cementoid can be present
49
How do odontogenic myxomas present on radiograph? (they are benign but locally aggressive)
Multilocular radiolucency
49
What is the histology of odontogenic myxomas?
Non-encapsulated, stellate fibroblasts + abundant connective tissue ground substance (glycosaminoglycans), sometimes odontogenic epithelium
50
How do cementoblastomas present on x-ray?
Well demarcated mottle/dense radiopaque, attached to root, root resorption, surrounded by thin radiolucent line
51
What is the histology of cementoblastoma?
Mass of calcified cementum-like materal w/ cells in lacunae, or cementicle-like, mass is uncalcified at periphery, cementoclasts, may recur if not remove completely
52
What does cemento-osseous dysplasia cover? (bone related diseases)
Periapical cemental dysplasia Florid cemento-osseous dysplasia
53
What is periapical cemental dysplasia?
Periapical radiolucency in the anterior mandible, of vital teeth, at apex Fibroblastic first then patches of sclerotic bone - cementifying fibroma
54
Why is cemento-osseous dysplasia different to condensing osteitis?
Condensing osteitis is associated with non-vital teeth
55
What is florid cemento-osseous dysplasia?
Bilateral and symmetrical, diffuse radiopaque masses of basophilic acellular cementum. No radiolucent border.
56
Who does cemeno-osseous dysplasia mostly occur in?
Afro-caribbean adult women
57
Malignant odontogenic tumours exist but are very rare. Give some examples.
Malignant ameloblastoma Ameloblastic carcinoma Primary intraosseous SCC Clear cell odontogenic carcinoma (w glycogen, but no mucin) Malignant change in odontogenic cysts Odontogenic sarcomas (malignant versions of AF and AFD)
58
Why should you not leave a cyst if benign?
Because a pathological epithelium can transform into malignancy
59
What tumours are there of unknown origin?
Melanotic neuroectodermal tumour of infancy - derived from neural crest, 2 cell types: neuroblast-like & polygonal epithelial pigmented forming 'alveoli' or gland-like structures Congenital gingival granular cell tumour (congenital epulis) - large closely packed granular cells, covered by squamous epithelium,

Oral pathology (27 decks)

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