OD: Odontogenic Neoplasms & Tumours

Odontogenic Tissues can be categorised into Epithelium of Origin or Mesenchyme of Origin.

List Odontogenic Tissues which are Epithelial in Origin (5)

1) Oral Epithelium

2) Dental Lamina

3) Enamel Organ

4) Reduced Enamel Epithelium

5) Rests of Malassez

Odontogenic Tissues can be categorised into Epithelium of Origin or Mesenchyme of Origin.

List Odontogenic Tissues which are Mesenchyme in Origin (3)

1) Dental Papilla - forms pulp of tooth (sits below enamel organ)

2) Dental Follicle - surrounds tooth bud, forming PDL

3) Periodontal Ligament

The Dental Lamina is a source of Odontogenic Epithelium (source of most odontogenic tumours). It Gives Rise to... (5)

1. Ameloblastoma 

2. Ameloblastic fibroma 

3. CEOT (Calcified Epithelial Odontogenic Tumour)

4. Keratocyst- NOT an odontogenic tumour. 

5. Gingival cysts- NOT an odontogenic tumour.

Radiographically, how do Odontogenic Tumours tend to present? (3)

1) Most present as Radiolucent Lesions

2) Some contain Calcifications

3) Most often present at the angle of the Mandible

Benign Odontogenic Tumours are classified by Histogenesis. List them (3)

1) Odontogenic Epithelium alone

2) Odontogenic Epithelium and Odontogenic Mesenchyme +/- Dental Hard Tissues

3) Odontogenic Mesenchyme Alone

What is the term given to a Malignant Odontogenic Tumour risen from Epithelium?

Carcinoma

What is the term given to a Malignant Odontogenic Tumour risen from Mesenchyme?

Sarcoma

Describe the Epidemiology of Odontogenic Tumours

- Very Rare

- 99% benign

- Ameloblastoma is the most common neoplasm

Where are the 3 different sources benign odontogenic tumours can arise from?

• Odontogenic epithelium alone (group 1 WHO)

• Odontogenic epithelium and odontogenic mesenchyme +/- dental hard tissues. (grp 2)

• Odontogenic mesenchyme alone. (Grp 3)

Odontomes are not Neoplasms. Explain why

Odontomes are Harmatomas.

These are malformations growing during the growth phases of a patient, when growth stops, the odontomes stop growing also. They do not behave like Neoplasms

List Odontogenic Tumours which are of only Epithelial Origin?

1) Ameloblastoma

2) Adenomatoid Odontogenic Tumour (AOT)

3) Calcifying Epithelial Odontogenic Tumour (CEOT)

4) Squamous Odontogenic Tumour (SOT)

What is an ameloblastoma?

A Benign but locally destructive odontogenic tumour arise from Epithelial Tissue

Which age groups do Ameloblastomas affect?

30 to 50

black people

Where do Ameloblastomas commonly affect?

80% are found in the Mandible, most at the angle (but can occur anywhere in jaws)

More aggressive in maxilla

Once it exits bone and enters soft tissues - easier expansile growth - harder to treat

Why do Ameloblastomas more commonly affect the Angle of the Mandible?

Ameloblastoma arise from the Dental Lamina which is Epithelial in Origin.

Most Dental Lamina is found at the angle of the mandible

Describe 4 Features of Ameloblastoma?

1) Often Asymptomatic

2) Bucco-Lingual Expansion - degree of facial swelling

3) Root Resorption or Displacement

4) Commonly Multi-locular but can be Uni-locular on Radiographs

How can you differentiate an Odontogenic Keratocyst from an Ameloblastoma?

Amelobastoma have Bucco-Lingual Expansion, whereas an Odontogenic Keratocyst have antero-posterior expansion

There are 3 Subtypes of Ameloblastoma. List them

1) Conventional Type (85%): Intra-Osseous

- Follicular

- Plexiform

2) Unicystic (14%): Intra-Osseous - less common and less aggressive

3) Peripheral (1%): Extra-osseous/gingiva - may arise in soft tissues of gums

Describe the Follicular Pattern of an Ameloblastoma (3)

1) Columnar Ameloblast Like Cells at the Periphery

2) Stellate Reticulum-Like area in the Centre

3) The Epithelium resembles the enamel organ, cysts form in the Stellate Reticulum like Areas.

Describe the Plexiform Pattern of an Ameloblastoma (3)

1) Columnar Ameloblasts - like cells forming Cords

2) Little or No Stellate Reticulum like areas

3) Cysts form in the Stroma

10-15% of Ameloblastomas are Unicystic.

What are the 4 Types of Unicystic Ameloblastomas

1) Luminal Type

2) Intraluminal Type

3) Mural Type

4) Multicystic Type

Which Unicystic Ameloblastomas are treated by Enucleation?

1) Luminal Type

2) Intraluminal Type

Which Unicystic Ameloblastomas are treated with Resection

1) Mural Type

2) Multicystic Type

Describe the Histological Appearance of Luminal Unicystic Ameloblastomas

Ameloblastoma lines a single cyst

Cyst lining has ameloblasts. Stellate reticulum. 

Rather than having a follicular appearance has a cystic lining.

Describe the Histological Appearance of Intraluminal Unicystic Ameloblastomas

Ameloblastoma lines a cyst and tumour proliferates into the Lumen

single cyst growing into lumen

How do you manage a Conventional Ameloblastoma?

- Excision with 10mm Margins to minimise recurrence

- Reconstruction needed - maybe with section of rib

- Maxilla more challenging to treat and restore

How do you manage a True Unicystic Ameloblastoma?

Refering to Luminal and Intraluminal Types:

- Enucleation and Careful Follow-Ups

How is a diagnosis made for an ameloblastoma?

Radiograph

Clinical exam and biopsy → can only tell if its unicystic after excision

What is an Adenomatoid Odontogenic Tumour (AOT)?

Benign tumour

From epithelial tissue

It does not recur and is probably a Hamartoma

What age & gender do AOTs affect and where are they usually found?

Age: 10-20, F>M

Mainly maxilla

What is the radiographic appearance of an AOT?

Radiolucency often around a tooth crown - may have calcifications

Can cause displacement of teeth

Mimic dentigerous cysts (can be a differential to it)

Most commonly occur around impacted canines

How do you differentiate a Dentigerous Cyst from an Adenomatoid Odontogenic Tumour?

AOT and Dentigerous Cyst affect unerupted teeth and the radiolucency attaches at the ACJ

In AOT the radiolucency will have calcifications in it therefore have small radiopacities.

What is the Histological Appearance of an AOT?

Epithelial Cells forming sheets and Duct-Like Structures.

Calcification is common

What is the Treatment for an AOT?

Enucleation

What is a Calcifying Epithelial Odontogenic Tumour and what is its Epidemiology?

Benign locally destructive, similar to ameloblastoma, from odontogenic epithelium alone

Age: 10-60

2/3 in Mandible, molar region +/- unerupted tooth

What is the Radiological Appearance of a CEOT?

Radiolucency with Speckled Calcifications

Calcifications increase with Age

Much bigger than AOTs

Doesn’t have dentigerous relationship

What is the Histological Appearance of a CEOT?

Composed of Pleomorphic Epithelium with Calcifications

Enamel Matrix Material which may calcify

Cubodial Cells with Prickles

What is the Treatment for a CEOT?

As for Ameloblastoma

- Enucleation

- Resection

- Reconstruction

List 3 Odontogenic Tumours that arise from Epithelial Tissue, Mesenchyme Tissue +/- Dental Hard Tissue (group 2 WHO)

1) Ameloblastic Fibroma

2) Dentinogenic Ghost Cell Tumour

3) Odontomes

What is an Ameloblastic Fibroma and whats it epidemiology?

A benign, locally agressive mixed odontogenic tumour

Age <20

Often found in the Mandible

What is the radiological appearance of an Ameloblastic Fibroma?

Well Defined Radiolucency - No calcifications

- 80% associated with an unerupted tooth

What is the histological appearance of an Ameloblastic Fibroma?

- Branching Cords and Islands of Epithelium resembling Enamel Organ or Dental Lamina

- Characteristic Fine Cellular Stroma

What is a Dentinogenic Ghost Cell Tumour and what’s its epidemiology?

A benign mixed odontogenic tumour,

Well define, locally aggressive

V rare, 40-60, M>F, mandible and maxilla

What is the radiological appearance of a Dentinogenic Ghost Cell Tumour?

Radiolucency with some calcifications. Tend to be well-outlined and large

What is the Histological Appearance of a Dentinogenic Ghost Cell Tumour?

- Epithelium resembling Ameloblastoma

- Ghost Cells and Dentine

- Overlap with Calcifying Odontogenic Cyst

What do Ghost Cells look like?

Cells with No Nuclei within them

They can become calcified giving calcification on radiographs

What are Odontomes AKA odontoma and what is their epidemiology?

Are harmatomas - disorganised proliferation of tissue which is normal for that location

Has limited growth potential (unlike tumour)

Up to 20 yrs (can prevent eruption of developing dentition), Both mandible and maxilla

What is the radiological appearance of an Odontome?

Radiolucency containing tooth like structures

What are the two types of Odontomes?

1) Compound Odontome

2) Complex Odontome

What are Compound Odontomes and what’s their epidemiology?

- Twice as common as a complex odontome

- Maxilla > Mandible

- Incisor/Canine Regions

- Small and Non-Aggressive

- A collection of Denticles (Little Teeth)

What are Complex Odontomes and what’s their epidemiology?

- Mandible > Maxilla

- Premolar/Molar Regions

- Ages 10 to 25

- Often a missing tooth in the arch - tooth fuses to odontome

- A fused mass of haphazardly arranged tooth tissues but normal morphogenetic relations are preserved

What are the 3 Odontogenic Tumours that are Mesenchyme only in Origin? (WHO group 3)

1) Myxoma/Myxo-Fibroma

2) Odontogenic Fibroma

3) Cementoblastoma

What is a Myxoma & Fibromyxoma and what’s their epidemiology?

• A Benign Neoplasm

• Mesenchymal in Origin

• Tendency to recur

• Locally destructive

• 10-30 yrs

• Mandible> maxilla

What is the clinical appearance of a Myxoma?

Slow Growing Painless Swelling

What is the histological appearance of a Myxoma?

Triangular, Stellate Cells in Loose Myxoid Stroma

idek wtf that pic is

What is the treatment for a Myxoma?

Enucleation, Resection and Reconstruction (as for ameloblastoma)

What is the radiological appearance of a Myxoma?

Uni or Multi-Locular Radiolucency

- Soap Bubble Appearance

- Root Displacement or Resorption

What is an Odontogenic Fibroma and what’s their epidmiology?

Benign Odontogenic Neoplasm - Mesenchymal in Origin

Wide age range, F>M

Mandible=maxilla

Not as aggressive

What are the two types of Odontogenic Fibromas?

Central and Peripheral

What is the Radiological Appearance of an Odontogenic Fibroma?

Unilocular radiolucency

What is the Histological Appearance of an Odontogenic Fibroma?

Mature Fibrous Tissue

Occasional Odontogenic Epithelial Rests but not a neoplastic part of the tumour

What is a Cementoblastoma and what is its epidemiology?

Benign odontogenic tumour originated from mesenchymal cells

Neoplasm of Cementoblasts

10-40, mandibular molars affected

What is the radiological appearance of a Cementoblastoma?

Radiopaque Lesion attached to Tooth Root with a Radiolucent Margin

What is the Histological Appearance of a Cementoblastoma?

Sheets of Cementum and Osteoid in a Mosaic Pattern, many plump Cementoblasts

- Resemble Osteoblastoma

What is the Treatment for Cementoblastoma?

Surgical Excision

Malignant Odontogenic Tumours are very rare.

What are the 4 Malignant Odontogenic Tumours

1) Ameloblastic Carcinoma - appears like SCC with ameloblasts dotted around - abnormal mitoses, pleomorphsm, destructive growth, poorly defined edge

2) Primary Intra-Osseous Carcinoma

3) Clear Cell Odontogenic Carcinoma

4) Malignant Variants of Other Tumours/Cysts