L13 Odontogenic tumours Flashcards
Which tissue do odontogenic tumours arise from?
Epithelium within bone of the jaws
Describe the histological appearance of odontogenic tumours.
- Variable appearance due to pluripotent nature of odontogenic epithelium
- May resemble a developing tooth
- May contain dental hard tissues e.g. enamel, dentine, cementum
Are odontogenic tumours rare?
- Yes, all are rare
- Ameloblastoma is the most common odontogenic tumour type
How are benign odontogenic tumours classified?
3 categories:
- Odontogenic epithelium only (no odontogenic mesenchyme = no hard tissue)
- Mixed odontogenic epithelium (some, but not all, can develop hard tissue)
- Mesenchyme and/or odontogenic ectomesenchyme (can present with or without odontogenic epithelium, tend to be inactive)
Are odontomes actually true tumours?
No, they are developmental anomalies known as hamartomatous lesions.
Name the 4 odontogenic tumours with odontogenic epithelium only.
- Ameloblastoma
- Squamous odontogenic tumour
- Calcifying epithelial odontogenic tumour
- Adenomatoid odontogenic tumour
Describe the main features of ameloblastomas.
- Most common benign odontogenic tumour
- Odontogenic epithelium without odontogenic mesenchyme
- Locally invasive neoplasm
- 1% of oral tumours
- 3 common types: conventional (solid/multicystic), unicystic, peripheral
Where are ameloblastomas most common?
- 80% mandible, 20% maxilla
In the mandible: - 70% are in the molar region
- 20% premolar
- 10% incisor
What age are ameloblastomas most commonly seen in?
- 4th and 5th decades of life
What are the symptoms of an ameloblastoma?
- Slow growing so may be asymptomatic
- Gradually increasing facial deformity, expansion of the jaw
What are the signs of an ameloblastoma?
- Bony hard, non tender, ovoid swelling
- Egg shell crackling on palpation in advanced cases
- Perforation of bone and spread to soft tissues (late stage)
- In the maxilla large tumours may produce little swelling, mandibular tumours tend to present at a smaller size
Describe the radiographic features of an ameloblastoma.
- Mostly multicolular (soap bubble appearance), but unilocular when small
- Well defined, corticated outline
- Uniformly radiolucent with radiopaque septa
- Expansion of buccal/lingual bone
- Teeth displaced
- Roots of involved teeth may be resorbed
- Often associated in the mandible with unerupted 3rd molars and misdiagnosed as dentigerous cysts
How are ameloblastomas managed?
Surgical excision due to locally invasive nature.
Some even require segmental resection involving portions of the mandible if very large.
What are the 2 possible histological presentations of an ameloblastoma?
- Follicular pattern
- Plexiform pattern
Describe follicular-type ameloblastoma.
Histological description
- Discrete round islands or follicles
- Resemble the enamel organ of the tooth germ
- Central mass of loosely connected angular cells resembling stellate reticulum
- Peripheral layer of cuboidal or columnar cells resembling ameloblasts (with reverse polarity)
- Follicles are seperated by fibrous tissue
- Follicles may show cystic breakdown, squamous metaplasia (epithelium becomes squamous like) and granular cell change
What type of polarity do ameloblast cells in ameloblastomas exhibit?
Reverse polarity.
Nuclei at opposite end to BM.
Describe plexiform-type ameloblastoma.
- Tangled network of strands and irregular masses showing the same cell layers as the follicular pattern
- Peripheral layer of ameloblast-like columnar cells with central stellate reticulum like cells
Where do researchers beleive the epithlieum in ameloblastomas originates from?
- Dental lamina or glands of Serres thought to be most likely
Other theories include: - Enamel organ
- HERS or rests of Malassez
- Epithelial lining of odontogenic cysts
- Basal layer of oral epithelium
How are ameloblastomas treated?
Depends on type
For conventional ameloblastoma:
- Surgical resection with margin of normal bone
- High risk of recurrence after curettage (not used)
- Long term follow up, recurrence can occur up to 10 years post op
Describe the main features of adenomatoid odontogenic tumours.
- Odontogenic epithelium without odontogenic ectomesenchyme
- Duct-like structures
- May be parly cystic
- Slow growing
What type of patient is an adenomatoid odontogenic tumour most commonly seen in?
- 2nd or 3rd decades of life
- More common in women
Where are adenomatoid odontogenic tumours most commonly found?
- Maxilla twice more common than the mandible
- Anterior maxilla most common, especially in the canine area
What are the symptoms and signs of adenomatoid odontogenic tumours?
Symptoms: slowly enlarging painless swelling
Signs: often associated with an unerupted tooth, rare extra-osseus lesions usually found in anterior maxillary gingivae
Usually found coincidently radiographically.
What are adenomatoid odontogenic tumours commonly misdiagnosed as?
Dentigerous cysts.
Remember dentigerous cysts are always attached at the ACJ, these tumours are not.
Describe the radiographic features of adenomatoid odontogenic tumours.
What tumour does this image show?
An adenomatoid odontogenic tumour, note how it is attached to the entire tooth, not just the ACJ.
Describe the histopathology of adenomatoid odontogenic tumours.
- Well encapsulated
- Solid or partly cystic
- Sheets, strands and masses of epithelium
- May differentiate into ameloblast-like cells in places
- Columnar cells form duct-like structures! Unique diagnostic feature.
- No reverse polarity of columnar cells.
What is the management for adenomatoid odontogenic tumours?
Enucleation.
- Don’t tend to recur due to limited growth potential, likely hamartomatous not neoplastic
- Major surgery not required
Describe the main features of calcifying epithelial odontogenic tumours.
What type of tissue do mixed odontogenic tumours contain?
- Odontogenic epithelium
- Mesenchyme
Name examples of mixed odontogenic tumours.
- Ameloblastic fibroma
- Odontoma: compound or complex
- Primordial odontogenic tumour (rare)
- Dentinogenic ghost cell tumour (rare)
Briefly describe ameloblastic fibromas.
- Odontogenic epithelium with odontogenic
ectomesenchyme, with or without dental hard
tissue formation - Rare benign tumour in which both epithelial
and mesenchymal elements are neoplastic
Which age group are ameloblastic fibromas most commonly found in?
Under 21s
Where are ameloblastic fibromas most commonly found?
- Premolar-molar region of the mandible
What are the symptoms of ameloblastic fibroma.
Tend to be asymptomatic.
Slowly enlarging painless swelling.
Describe the radiographic presentation of an ameloblastic fibroma.
- Well defined radiolucency
- Usually unilocular (may be multilocular when larger)
- Well defined, corticated outline
- Uniformly radiolucent with radiopaque septa
Describe the histopathology of an ameloblastic fibroma.
- Proliferating strands and islands of odontogenic epithelium in a highly cellular fibroblastic stroma resembling the dental papilla of a developing tooth
- Epithelial component show peripheral layer of columnar or cuboidal ameloblast‐like cells enclosing small amounts of stellate reticulum like cells
- May be narrow cell‐free zone of hyaline connective tissue around epithelial component
Describe the behaviour of ameloblastic fibromas.
- Benign
- Non-invasive
What was the old WHO classification of odontomas?
In 2017 there were 2 subtypes:
- Compound odontoma
- Complex odontoma
They have now been grouped together.
What are the signs and symptoms of odontomas?
- Often incidental findings
- May be found investigating an unerupted tooth
- May be large enough to expand bone
- Secondary infection may produce pain and swelling
Describe the radiographic features of odontomes.
- When fully formed they appear as a radiopaque mass
- Developing lesions show well define radiolucency containing radiopaque areas
Describe compound odontomes.
- Seen in the anterior maxilla most commonly
- Affects children
- Multiple tooth like structures
- 1-2cm in size
- Well organised enamel, dentine and pulp
Describe complex odontomes.
- < 20 years of age
- Posterior mandible
- Up to 3cm in size
- Impacts teeth or prevents eruption
- Spherical radiopaque mass
- Radiating peripheral radiopacities
- Radiolucent rim
- Haphazard dental structures
Describe the histopathology of a compound odontome.
- Separate denticles embedded in fibrous tissue
- Most denticles do not resemble normal teeth but in each one enamel, dentine, cementum and pulp arranged as in normal teeth
Describe the histopathology of a complex odontome.
- Mass of irregularly arranged but well formed enamel, dentine and cementum surrounded by a fibrous capsule
- Dentine forms bulk of lesion; pulp‐like tissue on surfaces not covered by enamel or cementum
How are odontomas managed?
- Enucleation
- Tooth may be extracted or left in situ
They are hamartomas with limited growth potential.
Name 4 mesenchymal odontogenic tumours.
- Odontogenic fibroma
- Odontogenic myxoma/myxofibroma
- Cementoblastoma
- Cemento-ossifying fibroma (a type of cemental lesion)
What are cemental lesions?
- Complex group with ill‐defined characteristics
- Some may be neoplastic
- Others may be dysplastic
- Some may be reactive processes
- Some share similarities with primary diseases of bone
- Significant changes in new WHO classification
What is a cementoblastoma?
A mesenchymal odontogenic tumour
- True benign neoplam
- Seen in those under 25
- Predominantly men
Where are cementoblastomas most commonly found?
- Molar or premolar areas
- Attached to the root of the tooth
- Mandibular first permanent molar most commonly affected
What are the symptoms of a cementoblastoma?
- Slowly enlarging swelling
- May be painful
- Can cause buccal expansion
Describe the radiographic features of a cementoblastoma.
- Well demarcated
- Mottled or dense radiopaque mass with radiolucent margin
- Attached to root of tooth which may show root resorption
Describe the histopathology of cementoblastomas.
- Mass of calcified cementum‐like tissue with many reversal lines
- Scattered cells in lacunae
- Uncalcified matrix at the periphery formed by
plump cementoblasts - Similar to osteoblastoma of bone
Describe the behaviour of cementoblastomas.
- Benign tumour
- Does not recur
- Need to be removed with the associated tooth
Describe odontogenic myxomas.
Describe the radiological presentation of odontogenic myxomas.
Uniformly radiolucent with radiopaque septa.
Multilocular.
Well defined, corticated outline.
Give examples of malignant odontogenic tumours.
- Ameloblastic carcinoma
- Primary intraosseus carcinoma
- Sclerosing odontogenic carcinoma
- Clear cell odontogenic carcinoma
- Ghost cell odontogenic carcinoma
