Odontogenic Tumours

Question 1

What epithelium can odontogenic tissues arise from?

Answer 1

Epithelium:
Oral epi
Dental lamina
Enamel organ
Reduced enamel epi
Rests of malassez 

Mesenchyme:

• Dental papilla
• Dental follicle
• Periodontal ligament

Question 2

What arises from hertwig’s root sheath?

Answer 2

Radicular cysts

Question 3

What arises from the reduced enamel epithelium?

Answer 3

Dentigerous cysts

Question 4

What arises from the dental lamina?

Answer 4

Ameloblastoma
Ameloblastic fibroma
CEOT
Keratocyst
Gingival crest

Question 5

What are odontogenic tumours most present as? Where?

Answer 5

Most present as radiolucent lesions
Some may contain calcifications
Most often at angle of mandible as arise from dental lamina = 8 is last use of dental lamina

Question 6

Classification of odontogenic tumours?

Answer 6

Benign

• Odontogenic epithelium alone = GROUP 1
• Odontogenic epithelium and odontogenic mesenchyme +/- dental hard tissues
• Odontogenic mesenchyme alone

Malignant
- Carcinomas and sarcomas

Question 7

Epidemiology of odontogenic tumours?

Answer 7

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

Question 8

What makes up group 1: odontogenic epithelium alone?

Answer 8

Ameloblasoma
Adenomatoid odontogenic tumour (AOT)
Calcifying epithelial odotogenic tumour (CEOT)
Squamous odontogenic tumour (SOT)

Question 9

Ameloblastoma features?

Answer 9

Benign but locally destructive

Uni or multi-locular radiolucency

Question 10

Ameloblastoma epidemiology?

Answer 10

Epidemiology:

• Age: 30-50
• 80% in mandible, most at angle

Question 11

Clinical presentation of ameloblastomas?

Answer 11

Clinical:

• Often asymp until obstruction of nerves
• Bucco-lingual expansion
• Root resorption or displacement

Uni or multi-locular radiolucency
Medial pterygoid muscle attachment onto pterygoid plates at lingual side of mandible - muscle can be affected

Question 12

Ameloblastoma subtypes?

Answer 12

1. Conventional types: intra-osseous
   - Follicular
   - Plexiform
   = 85%
2. Unicystic: intra-osseous 14%
   - Younger patients 10-20
   - Mainly posterior mandible
3. Peripheral: extra-osseous/gingiva 1%

Question 13

Ameloblastoma histology?

Answer 13

Follicular pattern: Columnar ameloblast like cells at the periphery with reverse polarity
Stellate reticulum like area in the centre
Epithelium resembles the enamel organ and there are islands and trabeculae of epithelial cells in a CT stroma
Cysts form in stellate reticulum like areas

Plexiform pattern:

• Columnar ameloblasts like cells forming cords
• Epithelium forms strands and trabeculae of small, darkly staining epithelial cells in a CT stroma with few cells
• Little or no stellate reticulum like areas
• Cysts form in stroma

Question 14

Management of ameloblastoma?

Answer 14

Diagnosis via biopsy

Conventional ameloblastoma:

• Requires excision (1-2cm with margins of normal bone to remove any extension into the surrounding bone)
• Reconstruction if removing part of mandible
• Maxilla can be very challenging: Bones are thinner and are weak barriers to spread. Can invade up into the orbit ad the brain.

True unicystic (v rare, types 1 and 2)

• Enucleation but risk of recurrence
• Careful follow up

Question 15

Features of adenomatoid odontogenic tumour? How to treat?

Answer 15

Benign, does not recur, probably a hamartoma

Enucleation sufficient to cure - do not reoccur

Question 16

Epidemiology of adenomatoid odontogenic tumour?

Answer 16

Age 10-20, F>M

Most often in maxilla, especially unerupted maxillary canine

Question 17

Radiological appearance of of adenomatoid odontogenic tumour?

Answer 17

Radiolucency often around a tooth crown, may have calcifications - fine and speckled like a snow storm radiopaque appearance

Question 18

Histology of adenomatoid odontogenic tumour?

Answer 18

Epithelial cells forming sheets and duct like structures

Calcified material a bit like dentine

Question 19

Differential diagnosis of of adenomatoid odontogenic tumour?

Answer 19

Dentigerous cyst

Question 20

Calcifying epithelial odontogenic tumour (Pindborg tumour) features?

Answer 20

Benign but locally destructive

Question 21

Calcifying epithelial odontogenic tumour epidemiology?

Answer 21

10-60
2/3 in mandible, molar region +/- unerupted tooth
Symptoms lacking until a swelling appears

Question 22

Calcifying epithelial odontogenic tumour radiological appearance?

Answer 22

Radiolucency with speckled calcifications, increasing radiopacity as it matures
Poorly defined margins

Question 23

Calcifying epithelial odontogenic tumour histology?

Answer 23

Composed of pleomorphic epithelium with calcifications, dentinoid and amyloid
Enamel matrix material which may calcify
Cuboidal cells with prickles
Large flat cells with a single nucleus in them

Question 24

Calcifying epithelial odontogenic tumour treatment?

Answer 24

Like ameloblastoma - surgical removal with margins, reconstruction or enucleation

Question 25

Is the odontogenic keratocyst a tumour?

Answer 25

Clinical evidence: - Pattern of recurrence - Link to NBCCS (gorlin goltz) Genetic evidence - PTCH mutations (9q22-31) - Clonality evidence?

Question 26

Group 2 odontogenic epithelium and odontogenic mesenchyme +/- dental hard tissues types?

Answer 26

Ameloblastic fibroma Dentinogenic ghost cell tumour Odontomes

Question 27

Benign or malignant - ameloblastic fibroma?

Answer 27

Benign

Question 28

Ameloblastic fibroma epidemiology?

Answer 28

<20 | Often in mandible

Question 29

Ameloblastic fibroma radiology?

Answer 29

Well defined radiolucency | 80% associated with unerupted tooth

Question 30

Ameloblastic fibroma histology?

Answer 30

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

Question 31

Dentinogenic ghost cell tumour features?

Answer 31

Benign

Question 32

Dentinogenic ghost cell tumour epidemiology?

Answer 32

V rare 40-60 M>F Mandible or maxilla

Question 33

Dentinogenic ghost cell tumour radiology?

Answer 33

Radiolucency, may have calcifications

Question 34

Dentinogenic ghost cell tumour histology?

Answer 34

``` Epithelium resembling ameloblastoma Ghost cells (nuclei disappear leaving white spots) and dentine Overlap with calcifying odontogenic cyst ```

Question 35

Odontomes features?

Answer 35

Hamartomas: benign malformations Up to 20 yrs old (developing dentition) May be mandible or maxilla Radiolucency containing tooth like structures

Question 36

Compound odontome features?

Answer 36

``` 2X more common as complex odontome Maxilla>mandible Incisor/canine regions Small and non-aggressive A collection of denticles (mini teeth) ```

Question 37

Complex odontome features?

Answer 37

``` Mandible > maxilla Premolar/molar regions 10-25yr age group Often a missing tooth in the arch A fused mass of haphazardly arranged tooth tissues but normal morphogenic relations are preserved Enucleated and removed = do not recur ```

Question 38

Group 3 odontogenic mesenchyme alone types?

Answer 38

Myxoma/myxo-fibroma Odontogenic fibroma Cementoblastoma

Question 39

Myxoma and fibromyxoma features?

Answer 39

Benign but locally destructive

Question 40

Myxoma and fibromyxoma epidemiology?

Answer 40

10-30yrs | Most in mandible

Question 41

Myxoma and fibromyxoma clinical features?

Answer 41

Slow growing, painless swelling

Question 42

Myxoma and fibromyxoma radiology?

Answer 42

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

Question 43

Myxoma and fibromyxoma histology?

Answer 43

Triangular/stellate cells in loose myxoid stroma | Pale staining with spindle cells

Question 44

Myxoma and fibromyxoma treatment?

Answer 44

As for ameloblastoma | - excision with a margin

Question 45

Odontogenic fibroma features?

Answer 45

``` Wide age range M>F Md = Mx Central and peripheral types Most often unilocular radiolucency Histology: mature fibrous tissue, variable amounts of inactive odontogenic epithelium ```

Question 46

Cementoblastoma?

Answer 46

Benign 10-40 Usually mandible, affecting molar teeth Radiopaque lesion ATTACHED TO TOOTH ROOT Histo: Sheets of cementum and osteoid in a mosaic pattern, many plump cementoblasts Resembles osteoblastoma

Question 47

Malignant odontogenic tumours? Types?

Answer 47

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