Odontogenic tumours Flashcards by Rachel Sladden

Odontogenic tissues (8)

Epithelium
-oral epithelium
-dental lamina
-enamel organ
-reduced enamel epithelium
-rests of Malassez
Mesenchyme
-dental papilla
-dental follicle
-periodontal ligament

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Remnants of odontogenic tumours and their possible consequences (3)

Hertwig’s root sheath –> radicular cysts
Reduced enamel epithelium –> dentigerous cysts
Dental lamina –> ameloblastoma, ameloblastic fibroma, CEOT, keratocyst, gingival cysts

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Odontogenic tumours (3)

Most present as as radiolucent lesions
Some may contain calcifications
Most often at angle of mandible

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Classification of odontogenic tumours (4)

Benign:
-odontogenic epithelium alone
-odontogenic epithelium and odontogenic mesenchyme +/- dental hard tissues
-odontogenic mesenchyme alone
Malignant:
-carcinomas and sarcomas

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Epidemiology of odontogenic tumours (4)

Odontogenic neoplasms are rare
Less than 1% of all tumours
Ameloblastoma is most common neoplasm
Odontomes are not neoplasms

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Ameloblastoma epidemiology (3)

Benign, but locally destructive
Age 30-50
80% in mandible, most at the angle

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Ameloblastoma: clinical (4)

Often asymptomatic
Bucco-lingual expansion
Root resorption or displaceent
Uni- or multi-locular radiolucency

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Ameloblastoma - subtypes (3)

Conventional type: intra-osseus (85%)
- follicular
- plexiform (many tumour contain both patterns)
Unicystic: intra-osseus (14%)
Peripheral: extra-osseus/ gingiva (1%)

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The follicular pattern of ameloblastoma (histology) (4)

Columnar ameloblast like cells at the periphery
Stellate reticulum-like area in the centre
The epithelium resembles the enamel organ
Cysts form in stellate reticulum-like areas

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The plexiform pattern of ameloblastoma (histology) (3)

Columnar ameloblast like cells forming cords
Little or no stellate reticulum-like areas
Cysts form in stroma

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Unicystic ameloblastoma types (literature supporting this is very poor) (4)

True unicystic ameloblastomas - can be ennucleated:
-luminal type
-intraluminal type
Variants of conventional ameloblastoma - should be excised with a margin (2)
-mural type
-multicystic type

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Management of ameloblastoma: conventional ameloblastoma (3)

Requires excision (with margins)
Reconstruction
Maxilla can be very challenging

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Management of ameloblastoma: true uicystic (very rare) (2)

Enucleation

Careful follow up

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Adenomatoid odontogenic tumour epidemiology and cure (4)

Benign, does not recur, probably a hamartoma
Age 10-20, F>M
Most often in maxilla
Enucleation sufficient to cure

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Adenomatoid odontogenic tumour radiology (2)

Radiolucency often around a tooth crown, may have calcifications
Differential diagnosis: dentigerous cyst

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Adenomatoid odontogenic tumour histology (2)

Epithelial cells forming sheets and duct-like structures

Calcification common

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Calcifying epithelial odontogenic tumour (‘Pindborg tumour’) epidemiology (3)

Benign but locally destructive
Age 10-60
2/3 in mandible, molar region +/- u/e tooth

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Calcifying epithelial odontogenic tumour (‘Pindborg tumour’) radiology (1)

Radiolucency with speckled calcifications

Calcifying epithelial odontogenic tumour (‘Pindborg tumour’) histology (2)

Composed of ‘pleomorphic’ epithelium with calcifications, ‘dentinoid’ and amyloid
Cuboidal cells with ‘prickles’

Calcifying epithelial odontogenic tumour (‘Pindborg tumour’) treatment (1)

As for ameloblastoma

Is the odontogenic keratocyst a tumour? (3)

Clinical evidence
-pattern of recurrence
-link to NBCCS (gorlin-Goltz)
Genetic evidence
-PTCH mutations (9q22-31)
-clonality?
In 2005, the WHO changed the name to keratocystic odontogenic tumour (KCOT): this was reversed in the 2017 classification

Group 2: Odontogenic epithelium and

Odontogenic mesenchyme +/- dental hard tissue (3)

Ameloblastic fibroma
Dentinogenic ghost cell tumour
Odontomes - covered in an earlier lecture

Ameloblastic fibroma epidemiology (3)

Benign
Age <20
Often in mandible

Ameloblastic fibroma radiology (2)

Well defined radiolucency

80% associated with unerupted tooth

Ameloblastic fibroma histology

Branching cords and islands of epithelium resembling enamel organ or dental lamina Characteristic fine cellular stroma

Dentinogenic ghost cell tumour epidemiology (4)

``` Benign Very rare Age most 40.60 M>F Mandible or maxilla ```

Dentinogenic ghost cell tumour radiology (1)

Radiolucency, may have calcifications

Dentinogenic ghost cell tumour histology (3)

Epithelium resembling ameloblastoma Ghost cells and dentine Overlap with calcifying odontogenic cyst

Odontomes (4)

Hamartomas: benign malformations Age: up to 20 (developing dentition) May be mmandible or maxilla Radiolucency containing tooth-like structure

Compound odontome (5)

* Twice as common as complex odontome * Maxilla > Mandible * Incisor / Canine regions * Small and non-aggressive * A collection of ‘denticles’ (mini-teeth)

Complex odontome (5)

``` • Mandible > Maxilla • Premolar / Molar regions • 10 – 25 year age group • Often a missing tooth in the arch • A fused mass of haphazardly arranged tooth tissues but normal morphogenetic relations are preserved ```

Group 3: odontogenic mesenchyme alone (3)

* Myxoma/myxo-fibroma * Odontogenic Fibroma * Cementoblastoma

Myxoma and fibromyxoma epidemiology (3)

Benign but locally destructive 10-30 years Most in mandible

Myxoma and fibromyxoma: clinical (1)

Slow growing painless swelling

Myxoma and fibromyxoma radiology (3)

Uni- or multi-locular radiolucency 'Soap-bubble' appearance Root displacement or resorption

Myxoma and fibromyxoma histolgoy (2)

Triangular/ stellate cells in loose myxoid stroma

Myxoma and fibromyxoma treatment (1)

As for ameloblastoma

Odontogenic fibroma (4)

• Wide age range, F

Odontogenic fibroma histolgoy (2)

• mature fibrous tissue, • variable amounts of inactive odontogenic epithelium

Cementoblastoma epidemiology (3)

Benign Age 10-40 Usually mandible, affecting molar teeth

Cementoblastoma radiology (2)

Radiopaque lesion attached to tooth root

Cementoblastoma histology (2)

Sheets of cementum and osteoid in a mosaic pattern; many plump cementoblasts Resembles osteoblastoma

Malignant odontogenic tumour (3)

``` Very rare Odontogenic carcinomas • Ameloblastic carcinoma • Primary intra-osseous carcinoma • Clear cell odontogenic carcinoma • Malignant variants of other tumours/cysts Odontogenic sarcomas ```