odontogenic tumours

Question 1

why/how are most odontogenic tumours discovered

Answer 1

non eruption of teeth
late stage bony expansion
incidental finding due to imaging for another reason

Question 2

why can only mixed odontogenic tumours have enamel and dentine formation

Answer 2

due to concept of induction
they stimulate each others growth

Question 3

what are the 5 odontogenic tumours

Answer 3

epi - ameloblstoma, calcifying epithelial OT, adenomatoid OT
mes - odontogenic myxoma
mixed - odontoma

Question 4

radiographic presentation of ameloblastoma

Answer 4

well defined, corticated margins that may be scalloped
primarily radiolucent
knife edge ERR
displacement of adjacent structures
thinning of bony cortices

Question 5

what direction do ameloblastomas grow

Answer 5

in all directions fairly equally

Question 6

how are ameloblastomas classified radiographically

Answer 6

multicystic - may have curved septae giving soap bubble appearance (90% cases)
unicystic - younger patients, lower recurrence risk, no scalloped margins

Question 7

2 most common histological forms of ameloblastoma

Answer 7

follicular
plexiform

Question 8

what form of ameloblastoma may present as a radiopaque lesion

Answer 8

desmoplastic

Question 9

follicular ameloblastoma

Answer 9

islands present within fibrous tissue background
islands bordered by ameloblast like cells which have darkly staining nucleus (hyperchromatic), columnar in shape and palisading arrangement
tissue in middle of islands will resemble stellate reticulum of tooth germ

Question 10

plexiform ameloblastoma

Answer 10

ameloblast like cells almost back to back with minimal stellate reticulum like tissue between
fibrous tisse will also be present

Question 11

do ameloblasts have a fibrous tissue capsule

Answer 11

no
cells can infiltrate surrounding jaw bone - difficult to eradicate, recurrence rates up to 15%

Question 12

how are ameloblastomas treated

Answer 12

surgical resection with margin

Question 13

classic presentation of an adenomatoid odontogenic tumour

Answer 13

unilocular radiolucency with internal calcifications around crown of an unerupted maxillary canine

Question 14

common epidemiology of adenomatoid odontogenic tumour

Answer 14

F>M
anterior maxilla
majority associated with unerupted canine
teenagers

Question 15

dentigerous cyst vs AOT

Answer 15

dentigerous cyst attaches at ECJ
AOT attaches apical to ECJ

Question 16

radiographic appearance of AOT

Answer 16

unilocular radiolucency
majority have some internal radiopacities which increase as tumour matures
margins are well defined and corticated
may displace adjacent structures
ERR is rare

Question 17

AOT histology

Answer 17

epithelial cells may be arranged in duct like or rosette like structures
minimal connective tissue present
degree of calcification may be noted

Question 18

do AOTs have a capsule

Answer 18

yes - well developed fibrous capsule - low recurrence rate

Question 19

management of AOT

Answer 19

majority treated by enucleation - associated tooth also removed
can also be treated with conservative local excision

Question 20

what are calcifying epithelial odontogenic tumours also known as

Answer 20

pindborg tumours

Question 21

odontogenic myxoma epidemiology

Answer 21

20s
F>M
mandible>maxilla

Question 22

radiographic presentation of odontogenic myxoma

Answer 22

well defined radiolucency
small lesions unilocular, larger lesions multilocular with scalloped margins.
ERR rare
larger lesions may cause displacement
larger lesions may have interal ‘tennis racket’ appearance due to septae

Question 23

if present in maxilla what may be seen in large odontogenic myxoma

Answer 23

obliteration of maxillary sinus

Question 24

histology of odontogenic myxoma

Answer 24

made up of myxoid tissue which is loose and would be gelatinous in consistency
stellate cells present within myxoid tissue but few in number
may be islands of inactive epithelial cells (not dividing)

Question 25

do odontogenic myxomas have a capsule

Answer 25

no capsule
locally invasive
25% recurrence rate!

Question 26

what similarities to teeth do odontomas have

Answer 26

mature to a certain stage (dont grow indefinetly)
can be associated with other odontogenic lesions e.g dentigerous cyst
surrounded by dental follicle
lie above IAC

Question 27

what syndrome is associated with multiple odontomas

Answer 27

gardners syndrome

Question 28

what are the 2 different types of odontoma

Answer 28

compound
complex
(compound more common 2:1)

Question 29

radiographic presentation of odontomas

Answer 29

initally radiolucent but progressive deposition of radiopaque material as mineralisation of dental tissues occurs
mature lesions surrounded by dental follicle
compund may appear as multiple ‘mini teeth’ - denticles

Question 30

histological appearance of odontomes

Answer 30

both compound and complex will have dental hard tissue
dentine often seen
may be element of soft tissue present
as enamel is organic, it is dissolved by acids during slide preparation so enamel spaces are seen instead

Question 31

enamel and histology in odontomes

Answer 31

as enamel is inorganic it is dissolved out by acids during slide preparation
if enamel fully calcified - will appear as spaces
if still a large organic content then this may show within enamel space - ‘fishscale’ appearance