odontogenic tumours Flashcards
incidence
rare - 1% of OMF lesions sent for histopathological assessment in UK
are most benign or malignant?
benign 100:1
how are the majority discovered and why?
due to non-eruption of teeth, late-stage bony expansion or imaging for other reasons (ie incidental)
because the majority are asymptomatic
where do most arise?
within the bone of jaws
- rare cases within surrounding ST
what usually causes symptoms?
pain usually secondary to infection or pathological fracture
how are they classified?
based on their tissue of origin
classification
epithelial
mesenchymal
mixed (epithelium and mesenchyme)
which are the only tumours that can have dentine and enamel formation and why?
mixed tumours
due to the concept of induction - D forms first (odontoblasts) from mesenchyme then this induces ameloblasts and E formation - cannot have E without D first
odontogenic sources of epithelium
rests of malassez
rests/glands of serres
reduced enamel epithelium
rests of malassez
remnants of Hertwig’s epithelial root sheath
can get inactive ‘clumps’ remaining in PDL
rests/glands of serres
remnants of the dental lamina
forms tooth germs - can get inactive clumps remaining within jaws
reduced enamel epithelium
remnants of the enamel organ
covers crown of UE tooth
examples of epithelial tumours
ameloblastoma
adenomatoid odontogenic tumour (AOT)
calcifying epithelial odontogenic tumour (CEOT)
example of mesenchymal tumour
odontogenic myxoma
example of mixed tumour
odontoma (odontome)
radiographic appearance
highly variable
entirely radiolucent/mixed/entirely radiopaque
may change as tumour progresses
what % of cases are either ameloblastoma or odontoma?
> 50%
what is an ameloblastoma?
benign epithelial tumour
typical features of an ameloblastoma
locally destructive but slow growing
typically painless
incidence of ameloblastoma
1% of OMF tumours
what age range is ameloblastoma most common in and gender?
4th-6th decades
M>F
location of ameloblastoma
80% in posterior mandible
types of ameloblastoma - radiological
multi cystic (85-90%) - tends to be older patients unicystic - younger patients, lower recurrence risk
types of ameloblastoma - histological
follicular
plexiform
desmoplastic
(several other less common types)
ameloblastoma margins
well-defined, corticated potentially scalloped (not unicystic)
feature of multi cystic ameloblastoma
may have thick, curved septa - soap bubble appearance
ameloblastoma radiographic appearance
primarily radiolucent (but rare variants can be mostly radiopaque) - desmoplastic
ameloblastoma effects on adjacent structures
displacement
thinning of bony cortices
“knife edge” external RR
characteristic expansion of ameloblastoma
all directions equally
histology of follicular ameloblastoma
ameloblast-like cells stellate reticulum like tissue cystic changes within islands within fibrous tissue background tissues within follicles loose can get squamous metaplasia change
histology of plexiform ameloblastoma
ameloblast-like cells - strands
may have small amount of stellate reticulum like tissue between
fibrous tissue stroma
does ameloblastoma have a CT capsule and what is the consequence?
no
cells can grow and infiltrate
reason for high recurrence rate
management of ameloblastoma
surgical resection with margin
recurrence of ameloblastoma
relatively common - up to 15% of cases
risk of malignant transformation of ameloblastoma
<1% of cases
ameloblastic carcinoma
what type of tumour is an adenomatoid odontogenic tumour?
benign epithelial tumour
classic presentation of AOT
unilocular radiolucency with internal calcifications around crown of unerupted maxillary canine
incidence of AOT
3% of odontogenic tumours
most common in 2nd decade
F>M
where do most AOTs occur?
anterior maxilla
what percentage of AOTs are associated with an UE tooth and what tooth commonly is it?
75%
commonly U3 - impedes eruption
presentation of an AOT
similar to dentigerous cyst but typically attached apical to CEJ
- asymmetric, involves root and crown
unilocular radiolucency
majority have internal calcifications/radiopacities
- increase as tumour matures
margins well-defined and corticated/sclerotic
may displace adjacent structures but external root resorption rare
histology of AOT
distinctive with patchy calcification
duct-like structure/sheets/rosette - epithelial
fibrous capsule - removal simple and low recurrence rate
what type of tumour is a calcifying epithelial odontogenic tumour?
benign epithelial tumour
what is CEOT also known as?
Pindborg tumour
incidence of CEOT
1% of odontogenic tumours
most common in 5th decade
M>F
most common site for CEOT
posterior mandible
presentation of CEOT
slow-growing but can become large 1/2 associated with UE tooth radiolucency often with internal radiopacities - calcifications of varying sizes variable radiographic presentation otherwise - unilocular/multilocular - margins: well/poorly defined - internal septal: none/fine/coarse
what type of tumour is an odontogenic myxoma?
benign mesenchymal tumour
incidence of odontogenic myxoma
3-6% of odontogenic tumours
most common in 3rd decade
F=M
site of predilection for odontogenic myxoma
mandible>maxilla
presentation of odontogenic myxoma
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 - septa geometric and at right angles
slow growth along bone before causing notable BL expansion
scallops between teeth but larger lesions may cause displacement
- external root resorption rare
histology of odontogenic myxoma
loose myxoid tissue with stellate cells
- loose type of CT can be gelatinous
may contain islands of inactive odontogenic epithelium
- vital but don’t divide (inert)
no capsule - locally invasive and infiltrate, harder to surgically remove, recurrence
management of odontogenic myxoma
curettage or resection (depending on size)
- scrape out if small
- cut a block out if larger
recurrence of odontogenic myxoma
high rate 25%
follow up important
lower recurrence rate if unilocular
what type of tumour is an odontoma?
benign mixed tumour
technically a hamartoma
malformation of dental tissue - E, D, C, P
odontoma similarities to teeth
mature to a certain stage (ie do not grow indefinitely)
can be associated with other odontogenic lesions (e.g. dentigerous cysts)
surrounded by dental follicle
lie above IDC
incidence of odontoma
1/5-2/3 of all odontogenic tumours
most common in 2nd decade
F=M
types of odontoma
compound
complex
compound>complex 2:1
compound odontoma
ordered dental structures
may appear as multiple “mini teeth” (denticles)
more common in anterior maxilla
complex odontoma
disorganised mass of dental tissue
more common in posterior body of mandible
histology of odontoma
enamel space
- inorganic so dissolved during prep - get spaces
- unless not fully calcified - may still see some parts
dentine
may see cementum
