Odontogenic Tumours Flashcards
Are they rare
Yes
1% of oral & maxillofacial lesions sent for histopathological assessment in UK
What non-cystic radiolucent lesions are there
Odontogenic tumours
-Amrloblastoma
-Ameloblastic fibroma
-Malignant ameloblastoma
-Odontogenic fibroma and myxoma
Giant cell lesions
-Peripherla and central giant cell granuloma
-Brown tumours of hyperparathyroid
-Cherubism
Fibro cemento osseous lesions
Radiolucent non-odontogenic tumours
-Chondroma
-Osteosarcoma
-Squamous cell carcinoma
Are they more bengin or malignant
Benign»_space; malignant (100:1)
What are the symptoms
Majority asymptomatic and discovered due to late eruption of teeth, late stage bony expansion or imaging for ther reasons
Where do they arrise
Mostly within bone of jaws
Whatare the classifications
Grouped based on there tissue of origin
-Epithelial
-Mesenchymal
-Mixed (only tumour to have dentine/enamel formation)
What are the odontogenic sources of epithelium of odontogenic tumours
Rests of Malassez
-Remnants of Hertwig’s epithelial root sheath
Rests of Serres
-Remnants of the dental lamina
Reduced enamel epithelium
-Remnants of the enamel organ
What is meant by the concept of induction
cannot have enamel without dentine
Odontoblasts forms dentine (mesenchymal origin) ameloblasts only start to form enamel once dentine is layed down, So the presence of dentine is important for induction of maturation of ameloblasts and then formation of enamel
What forms hertwigs epithelial root sheath
inner and outer odontogenic epithelium (on histology side its the bits forming the roots)
What forms the tooth germ
Dental lamina
Give examples of epithelial, mesenchymal and mixed tomours
Epithelial
-Ameloblastoma
-Adenomatoid odontogenic tumour
-Calcifying epithelial odontogenic tumour
Mesenchymal
-Odontogenic myxoma
Mixed
-odontoma
What are the radiographic features of a odontogenic tomour
Highly variable
> 50% of cases are either what
ameloblastoma or odontoma
What is a ameloblastoma and what is the incidence
Benign epithelial tumour
-Locally destructive but slow-growing
-Typically painless
inidence
-1% of oral & maxillofacial tumours
-Most common in 4th-6
the decades
-80% occur in posterior mandible
-M > F
What are the radiologically types of ameloblastomas
Multicystic (85-90%)
Unicystic
What are the histological types of ameloblastomas
Follicular
Plexiform
Desmoplastic
What are the radiograhpic features of a ameloblastoma
Margins
-Well-defined, corticated
-Potentially scalloped
Multicystic type
-May have thick, curved septa → “soap bubble” appearance
Primarily radiolucent
Adjacent structures
-Displacement
-Thinning of bony cortices
-“Knife edge” external root resorption
What is the histology of a follicular ameloblastoma
Islands with ameloblast like cells lining them with a fibrous tissue background
Ameloblast-like cells
Stellate reticulum like tissue, in the inside of the islands
Fibrous tissue
Cystic changes in the island
What is the histology of plxiform ameloblastoma
Ameloblast-like cells arranged in strands sometimes with stellate reticulum like tissue inbetween
Stellate reticulum like tissue
Fibrous tissue
What is the key thing about ameloblastomas and what does it result in
No Connective tissue capsule
Cells wont be stopped gorwing and infiltrating into jaw bone resulting in the high recurrence rate
What is the mangement of ameloblastomas
Surgical resection with margin
Recurrence relatively common, Up to 15% of cases
Risk of malignant transformation of ameloblastoma
<1% of cases
Ameloblastic carcinoma
What is a Adenomatoid odontogenic tumour (AOT) and what is its incidence
Benign epithelial tumour
Incidence
-3% of odontogenic tumours
- 2nd decade
-F > M
-Majority occur in anterior maxilla
What is the presentation of AOT
75% associated with an unerupted toothCommonly a maxillary canine
-Similar to dentigerous cyst but typically attached apical to cemento-enamel junction
-Impedes eruption
Unilocular radiolucency
Majority have internal calcifications/radiopacities
Margins well-defined & corticated/sclerotic
May displace adjacent structures but external root resorption is rare
asymmetrical
What is the histology of a AOT
Epithelial cells can present as a duct like structure or have a rosette apperance
Some calcification leading to distinctive patches
Well developed fibrous tissue capsule
What is a Calcifying epithelial odontogenic
tumour (CEOT) and what is its incidence
A benign epithelial tumour (Pindborg tumour)
Incidence
-1% of odontogenic tumours
-5th decade
-M > F
-Posterior mandible is most common site
What is the prsentation of CEOT
Slow-growing but can become large
Half associated with unerupted tooth
Radiolucency often with internal radiopacities
Calcifications of varying sizes
Variable radiographic presentation otherwise
-Unilocular/multilocular
-Margins: well-defined/ poorly-defined
-Internal septa: none/fine/coarse
What is a Odontogenic myxoma and its incidence
Benign mesenchymal tumour
Incidence
-3-6% of odontogenic tumours
-3rd decade
-F = M
-Mandible > maxilla
What is the presentation of odontogenix myxoma
Well-defined radiolucency +/- thin corticated margin
Smaller lesions unilocular
Larger lesions multilocular with scalloped margins
-“Soap bubble” appearance
Slow growth along bone before causing notable
bucco-lingual expansion
Scallops between teeth but larger lesions may
cause displacement
External root resorption rare
What is the histology of a odontogenic myxoma
Loose myxoid tissue with stellate cells
May have smalls groups of odontogenic epithelium
May contain islands of inactive odontogenic epithelium
No capsule → locally invasive into adjacent bone
What is the management of odontogenic myxoma
Curettage or resection
High recurrence rate: 25%
-Follow-up important
-Lower recurrence rate if unilocular
What is a odontoma and what is its incidence
Benign mixed “tumour”
-Technically a hamartoma
Malformation of dental tissue
-Enamel, dentine, cementum & pulp
Similarities to teeth
-Mature to a certain stage
-Can be associated with other odontogenic lesions (e.g. dentigerous cysts)
-Surrounded by dental follicle
Lie above inferior alveolar canal
Incidence
-1/5 to 2/3’s of all odontogenic tumours
-2nd decade
-F = M
What are the types of odontoma
Compound odontoma
-Ordered dental structures
-May appear as multiple “mini teeth” (i.e. denticles)
-More common in anterior maxilla
Complex odontoma
-Disorganised mass of dental tissues
-More common in posterior body of mandible
Compound > complex (2:1)
What is the histology of a odontoma
Will have dental hard tissues
-Dentine and enamel space(as enamel inorganic so it get dissolved in prep)
What is mainly used for treating ameloblastoma and sarcoma and what ha[[ens
Segmental resection:
-Removal of cyst with margin of ‘normal’ bone
-Normally require secondary procedure for reconstruction of defect
