Odontogenic Neoplasms and 'Tumours' Flashcards
Aim: To provide an overview of odontogenic tumours Objectives: At the end of this lecture you should: - Know how odontogenic tumours are classified - Be aware of the range of odontogenic tumours - Know the basic pathology of the most common lesions - Be aware of how odontogenic tumours present - Be aware of malignant odontogenic tumours.
How can Odontogenic Neoplasms be classified? What types of Neoplasms go in each category? (1+3, 1+1)
Benign:
- Odontogenic epithelium alone
- Odontogenic epithelium and odontogenic mesenchyme +/- dental hard tissues
- Odontogenic mesenchyme alone Malignant:
- Carcinomas and Sarcomas
What are common clinical presentations of Odontogenic Tumours? (3)
- Present as radiolucent lesions
- Some may contain calcifications
- Most often at angle of mandible
List the odontogenic epithelium tissues (5)
- Oral epithelium
- Dental lamina
- Enamel organ
- Reduced enamel epithelium
- Rests of Malassez
List the odontogenic mesenchyme tissues (3)
- Dental papilla
- Dental follicle
- Periodontal ligament
Where do the remnants of Odontogenic Epithelium come from in Radicular Cysts? (1)
Hertwigs root sheath
Where do the remnants of Odontogenic Epithelium come from in Dentigerous Cysts? (1)
Reduced enamel epithelium
Where do the remnants of Odontogenic Epithelium come from in ameloblastomas, ameloblastic fibroma, CEOT, keratocysts and gingival cysts? (1)
Dental lamina
What is the dental lamina? (3)
- First evidence of tooth development in humans occurs at 6weeks of fetal life
- Proliferation of a horseshoe-shaped epithelial ridge from the basal layer of the primitive oral epithelium into the underlying mesoderm in the position of the future jaws; known as the dental lamina
- The dental lamina proliferates backwards in each arch, successively giving rise to the enamel organs of the future second deciduous molar and the three permanent molars
What is the epidemiology of odontogenic tumours? (4)
- Odontogenic neoplasms are rare
- Less than 1% of all oral tumours
- Ameloblastoma is most common neoplasm
- Odontomes are not neoplasms
What are the percentage prevalence’s of Ameloblastoma, Myxoma/myxofibroma, Calcifying odontogenic cyst (COC), Adenomatoid odontogenic tumour (AOT), Ameloblastic fibroma, Calcifing epithelial odontogenic tumour (CEOT), Squamous odontogenic tumour (SOT), Odontomes? What types of odontogenic tumours are they all? (15)
Ameloblastoma, 15% - Odontogenic epithelium alone (E)
Myxoma/myxofibroma, 10% Odontogenic mesenchyme alone (M)
Calcifying odontogenic cyst (COC), 4% Odontogenic epithelium and Odontogenic mesenchyme +/- dental hard tissue (E+M)
Adenomatoid odontogenic tumour (AOT), 3% Odontogenic epithelium alone (E)
Ameloblastic fibroma 2% Odontogenic epithelium and Odontogenic mesenchyme +/- dental hard tissue (E+M)
Calcifing epithelial odontogenic tumour (CEOT) 1.5% Odontogenic epithelium alone (E)
Squamous odontogenic tumour (SOT) 0.5% Odontogenic epithelium alone (E)
Odontomes 50%
List the Group 1: Odontogenic Epithelium alone – Odontogenic tumours (5)
- Ameloblastoma
- Adenomatoid odontogenic tumour (AOT)
- Calcifying epithelial odontogenic tumour (CEOT)
- Squamous odontogenic tumour (SOT)
- Clear cell odontogenic tumour
List the Group 2: Odontogenic epithelium and Odontogenic mesenchyme +/- dental hard tissue – odontogenic tumours (4)
- Calcifying odontogenic cyst (COC)
- Ameloblastic fibroma
- Ameloblastic fibro-odontome
- Odontomes – covered in an earlier lecture
List the Group 3: Odontogenic mesenchyme alone – odontogenic tumours (3)
- Myxoma/fibromyxoma
- Odontogenic Fibroma
- Cementoblastoma
List the prevalence and names of malignant odontogenic tumours (1,1+4,1)
- Very rare
- Odontogenic carcinomas
- Malignant ameloblastoma
- Primary intraosseous carcinoma
- Clear cell odontogenic carcinoma
- Malignant variants of other tumours/cysts
- Odontogenic sarcomas
What is the epidemiology of an Ameloblastoma? (2)
- Age: 30 - 50
- 80% in mandible, most at the angle
Describe an Ameloblastoma clinically (5)
- Benign but locally invasive
- Often asymptomatic
- Bucco-lingual expansion
- Root resorption
- Uni- or multi-locular radiolucency
What are the Ameloblastoma subtypes and what are their percentage prevalences? (1+2, 2)
- Solid/multicystic: intra-osseous 85%
- Follicular
- Plexiform
- Unicystic: intra-osseous 14%
- Peripheral: extra-osseous 1%
Describe the histology of the follicular subtype of Ameloblastoma (2)
- The epithelium resembles the enamel organ
- Cysts form in stellate reticulum
Describe the histology of the plexiform subtype of Ameloblastoma (1)
Cysts form in stroma
What are the three subtypes of Unicystic Ameloblastomas (3)
- Simple cyst ‘lumenal’
- Plexiform unicystic ‘intralumenal’
- Mural ameloblastoma
What are the prognoses and treatment for the different unicystic ameloblastomas? (2)
- 1 & 2: good prognosis and require enucleation only
- 3: behaves as a conventional ameloblastoma and must be managed accordingly
Describe the epidemiology of an Adenomatoid Odontogenic Tumour (2)
- Age: 10-20
- Often in maxilla
Describe the Adenomatoid Odonotgenic Tumour clinically (2)
- Benign, does not recur, probably a hamartoma
- Radiolucency often around a tooth crown, may have calcifications
What is the histology of an Adenomatoid Odonotgenic Tumour? (2)
- Epithelial cells forming sheets and duct-like structures
- Calcification common
What is the epidemiology of Calcifying Epithelial Odontogenic Tumour (‘Pindborg’s tumour’)? (2)
- Age: 10-60
- 2/3 in mandible, molar region +/- u/e tooth
Describe Calcifying Epithelial Odontogenic Tumour (‘Pindborg’s tumour’) clinically (2)
- Benign but locally invasive
- Radiolucency with speckled calcifications
Describe the histology of Calcifying Epithelial Odontogenic Tumour (‘Pindborg’s tumour’) (1)
Composed of ‘pleomorphic’ epithelium with calcifications, ‘dentinoid’ and amyloid
What is the clinical and genetic evidence to suggest that the odontogenic keratocyst in a tumour? What was its new suggested name? (1+2, 1+2, 1)
- Clinical evidence
- Pattern of recurrence
- Link to Basal Cell Carcinomas (Gorlin-Goltz)
- Genetic evidence
- PTCH mutations (9q22-31)
- Clonality?
- Keratocystic odontogenic tumour (KCOT) WHO 2005
What is the epidemiology of a Calcifying odontogenic cyst (COC)? (2)
- Age: 10-30
- Mandible or maxilla
Describe the Calcifying odontogenic cyst (COC) clinically
- Benign
- Radiolucency, may have calcifications
What is the histology of the Calcifying odontogenic cyst (COC)?
- Cyst lined by ameloblastoma-like epithelium with ghost cells and dentine in the wall
- May be solid – ‘odontogenic ghost cell tumour’
What is the epidemiology of the Ameloblastic Fibroma? (2)
- Age: < 20
- Often in mandible
Describe the Ameloblastic Fibroma (2)
- Benign
- Well defined radiolucency
Describe the histology of the Ameloblastic Fibroma (2)
- Branching cords and islands of epithelium resembling enamel organ or dental lamina
- Characteristic fine cellular stroma
Describe Odontomes (4)
- Hamartomas: benign malformations
- Age: up to 20 (developing dentition)
- May be mandible or maxilla
- Radiolucency containing tooth-like structures
Describe Compound Odontomes include prevalence and epidemiology (5)
- Twice as common as complex odontome
- Maxilla > Mandible
- Incisor / Canine regions
- Small and non-aggressive
- A collection of ‘denticles’ (mini-teeth)
Describe Compound Odontomes include prevalence and epidemiology (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
Describe Myxoma/fibromyxoma (5)
- Benign but locally invasive
- Epidemiology: 10 – 30 years
- Clinically slow growing painless swelling
- Uni- or multi-locular radiolucency
- “soap-bubble” appearance
Describe the epidemiology of the Cementoblastoma (2)
- Age: 10-40
- Usually mandible, affecting molar teeth
Describe the Cementoblastoma clinically (1)
Radiopaque lesion attached to tooth root
Describe the histology of the Cementoblastoma (2)
- Sheets of cementum and osteoid in a mosaic pattern; many plump cementoblasts
- Resembles osteoblastoma