odontogenic tumours Flashcards
occurence of odontogenic tumours
rare
1% of oral & maxillofacial lesions sent for histopathological assessment in UK
Benign»_space; malignant (100:1)
Majority asymptomatic
* Often discovered due to non-eruption of teeth, late-stage bony expansion or imaging for other reasons (i.e. incidental)
* Pain usually secondary to infection or pathological fracture
Mostly arise within the bone of the jaws
* Rare cases can be within the surrounding soft tissue
classification of odontogenic tumours
3 groups
epithelial
mesenchymal
mixed (epithelium and mesenchymal)
based on germ cell layer of tissue origin
which class of odontogenic tumour can have enamel/dentine formation
only mixed tumours
due to concept of induction
* means that formation of dental hard tissues in the tumours needs the presence of both types of tissues.
* Dentin formation (mesenchymal in origin) will induce maturation of ameloblasts and the formation of enamel (epithelial in origin).
In the other two groups, the tumour originates from one kind of tissue only so there is no hard tissue formation
3 odontogenic sources of epithelium
rests of malassez
rests of serres
reduced enamel epithelium
rests of malassez
Remnants of Hertwig’s epithelial root sheath (remnants of both inner and outer odontogenic epithelium; forms the outline of the hard tissues of the root)
rests of serres
Remnants of the dental lamina (responsible for the formation of the tooth germs – after tooth formation has ceased, DL will breakdown leaving small clumps of cells remaining)
reduced enamel epithelium
Remnants of the enamel organ (after crown formation complete; outer and inner enamel epithelium become close to each other and stellate reticulum covers the crown of the unerupted tooth?)
3 examples of epithelial odontogenic tumours
ameloblastoma
adenomatoid odontogenic tuumour
calcifying epithelial odontogenci tumour
example of mesenchymal odontogenic tumour
odontogenic myxoma
example of mixed odontogenic tumour
odontoma
‘-oma’ indicates
neoplasm
radiographic appearance of odontogenic tumour
Entirely radiolucent ↔ mixed ↔ entirely radiopaque
* May change as tumour progresses
> 50% of cases are either ameloblastoma or odontoma
* Debate over which is most common (due to issues with data collection & overall scarcity)
* Ameloblastoma often stated as more common but studies are based on histopathology results – odontomas arguably not often sent for histopathological assessment
what are ameloblastomas
Benign epithelial tumour
Locally destructive but slow-growing – cause damage locally
Typically painless
incidence of amleoblastomas
1% of oral & maxillofacial tumours
Most common in 30-60y
80% occur in posterior mandible
M > F
types of ameloblastoma
2 categories with subgroups
Radiological
* Multicystic (85-90%)
* Unicystic - Younger patients;Lower recurrence risk
Histological
* Follicular
* Plexiform
* Desmoplastic (more radiopaque than other typical ameloblastomas)
(Several other less common types)
radiographic characteristics of ameloblastomas
Margins
* Well-defined, corticated
* Potentially scalloped (undulating margin – only seen in multicytic type)
Multicystic type
* May have thick, curved septa - “soap bubble” appearance
Primarily radiolucent (but rare variants can be mostly radiopaque e.g. desmoplatic, sometimes if there is many septa can appear radiopaque)
Adjacent structures
* Displacement
* Thinning of bony cortices
* “Knife edge” external root resorption
characteristic pattern of expansion – expand in all direction equally
unlike odontogenic keratocyst – along the bone before buccal lingual expansion
radiological classifications of ameloblastoma
multicystic 85-90%
unicystic (younger pt, lower recurrence risk)
histologica classifications of ameloblastomas
3
Follicular
Plexiform
Desmoplastic (more radiopaque than other typical ameloblastomas)
(Several other less common types)
histologica classifications of ameloblastomas
3
Follicular
Plexiform
Desmoplastic (more radiopaque than other typical ameloblastomas)
(Several other less common types)
follicular ameloblastoma histology characteristics
4
Islands present in fibrous tissue background
Bordered by columnar cells with darkly staining nuclei (resemble ameloblast)
In middle of follicle – loose tissue, resembling the stellate reticulum of the tooth germ
Can have cystic changes within the tooth germ – varying sizes
plexiform ameloblastoma histology characterics
4
Same basic histology as the follicular
Arranged differently
* Ameloblastoma-like cells arranged in strands
* Stellate reticulum like tissue in between strands
* Can be back-back ameloblastoma-like cells with no stellate reticulum like in between
* Supported by fibrous tissue
plexiform ameloblastoma histology characterics
4
Same basic histology as the follicular
Arranged differently
* Ameloblastoma-like cells arranged in strands
* Stellate reticulum like tissue in between strands
* Can be back-back ameloblastoma-like cells with no stellate reticulum like in between
* Supported by fibrous tissue
key histological features of ameloblastomas
No connective tissue capsule in any ameloblastomas – means the tissue can infiltrate into jaw bone - high recurrence rate
describe this clinical case
16yo female with lump on lower jaw
* Present for some months
* Occasional pain initially but none now
* Gradually getting bigger
Clinical examination
* Hard, bony swelling located buccal to teeth 35-37
* Teeth not TTP
* Partially-erupted 38
Well defined corticated margins
Septae within
Thinning of inferior corticated margin of the mandible
Knife edge root resorption of the distal and mesial root of 36
Displacement of IDC
management of ameloblastoma
Surgical resection with margin (1cm of normal bone – prevent recurrence)
Recurrence relatively common
* Up to 15% of cases
Risk of malignant transformation
* <1% of cases
* Ameloblastic carcinoma
what is adenomatoid odontogenic tumour (AOT)
Benign epithelial tumour
“Unilocular radiolucency with internal calcifications around crown of unerupted maxillary canine” is classic presentation
incidence of adenomatoid odontogenic tumour (AOT)
3% of odontogenic tumours
Most common in 10-20y
F > M
Majority occur in anterior maxilla
75% associated with an unerupted tooth
* Commonly a maxillary canine
* Similar to dentigerous cyst but typically attached apical to cemento-enamel junction
* Impedes eruption
radiographic characteristics of adenomatoid odontogenic tumour
similar to dentigerous cyst but typically attached apical to CEJ
Unilocular radiolucency
Majority have internal calcifications/radiopacities
* Increase as tumour matures
Margins well-defined & corticated/sclerotic (thick unlike others)
May displace adjacent structures but external root resorption is rare
histology of adenomatoid odontogenic tumour
epithelial origin – arranged in duct like structures or sheets or rosette appearance
some calcification (seen in radiograph)
well developed fibrous tissue capsule surrounding the AOT - removal easier and recurrence low
describe this case
RFA - delayed eruption 33
radiolucent area around crown of 33 – bulges out around mesial aspect root – well defined corticated radiolucency, not symmetrical (rules our follicle or dentigerous cysts), involving root and crown - AOT
Tooth needs aid to erupt
what are calcifying odontogenic tumours (CEOT)
Benign epithelial tumour
a.k.a. Pindborg tumour
Incidence
* 1% of odontogenic tumours
* Most common in 5th decade
* M > F
* Posterior mandible is most common site
most common odontogenic tumours
ameloblastomas or odontomas (>50%)
odontomas the most common
incidence of calcifying epithelial odontogenic tumours (CEOT)
- 1% of odontogenic tumours
- Most common in 5th decade
- M > F
- Posterior mandible is most common site
presentation of calcifying epithelial odontogenic tumours
Slow-growing but can become large
Half are associated with an 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
Hard to dx
what are odontogenic myxomas
Benign mesenchymal tumour
Incidence
* 3-6% of odontogenic tumours
* Most common in 3rd decade
* F = M
* Mandible > maxilla
incidence of odontogenic myxomas
- 3-6% of odontogenic tumours
- Most common in 3rd decade
- F = M
- Mandible > maxilla
presentation of odontogenic myxomas
Well-defined radiolucency +/- thin corticated margin
* Smaller lesions - unilocular
* Larger lesions multilocular with scalloped margins
“Soap bubble” appearance
“Tennis racket” pattern of internal septa suggestive of myxoma but only occurs in minority of cases
Slow growth along bone before causing notable bucco-lingual expansion
Scallops between teeth but larger lesions may cause displacement
* External root resorption rare
histology of odontgenic myxoma
- Loose myxoid tissue with stellate cells
- May contain islands of inactive odontogenic epithelium
- No capsule so locally invasive
mesenchymal in origin
management of odotogenic myxoma
Curettage or resection (depending on size)
High recurrence rate: 25%
* Follow-up important
* Lower recurrence rate if unilocular
what are odontomes
benign mixed ‘tumour’
Technically a hamartoma not technically a neoplasm
Malformation of dental tissue
* Enamel, dentine, cementum & pulp
Similarities to teeth
* Mature to a certain stage (i.e. do not grow indefinitely)
* Can be associated with other odontogenic lesions (e.g. dentigerous cysts)
* Surrounded by dental follicle
* Lie above inferior alveolar canal
can cause impaction of teeth
aka odontoma
ortho calls them supernumeraries
incidence of odontomes
1/5 to 2/3’s of all odontogenic tumours
Most common in 2nd decade
F = M
2 types of odontomes
compound
complex
Compound > complex (2:1)
compound odontome
Ordered dental structures
* May appear as multiple “mini teeth” (i.e. denticles)
More common in anterior maxilla
complex odontome
Disorganised mass of dental tissues
More common in posterior body of mandible
what is the more common type of odontome
Compound > complex (2:1)
histology of odontome
Has dental hard tissue – originates from both epithelial and mesenchymal tissues
Dentine seen
Enamel is dissolved in slide preparation if fully calcified – spaces where it was (inorganic, if not fully calcified will have some organic substance left and can be seen)
