scr - os & histopathology - tumours Flashcards
odontogenic tumours
majority asymptomatic often discovered due to:
- non eruption of teeth
- late stage bony expansion
- incidental finding
pain is usually due to pathological # or 2ndary infection
3 groups of odontogenic tumour
- epithelial -> ameloblastoma / adenomatoid odontogenic tumour / calcifying epithelial odontogenic tumour
- mesenchymal -> odontogenic myxoma
- mixed (both of above) -> odontoma
mixed tumours specifically
can have enamel / dentine formation due to concept of induction
1st formed dentine from odontoblasts which are mesenchymal in origin
ameloblasts mature & form enamel only when dentine starts getting laid down so present of dentine crucial for induction for maturation of ameloblast formation of enamel
odontogenic sources of epithelium
rests of malassez - from hertwig’s epithelial root sheath
rests of serres - from dental lamina
reduced enamel epithelium - from enamel organ
ameloblastoma
benign epithelial tumour
locally destructive but slow growing & typically painless
1% of OMFS tumours
4th-6th decades most common
80% posterior mandible
M>F
radiographic appearance of ameloblastoma
well defined bone surrounding pathology
well defined corticated margins
scalloped & multicystic
thick curved septa i.e. soap bubble appearance
primarily radiolucent
adjacent structures to ameloblastoma
- displacement; characteristic expansion pattern (expands in all directions fairly equally)
- thinning of bony cortices
- ‘knife edge’ external root resorption
histopathological criteria of ameloblastoma
can be:
follicular
plexiform
desmoplastic
plexiform form
shows fibrous tissue / stellate reticulum like tissue / ameloblast like cells
no CT capsule
so cells can grow & infiltrate into jaw bone & is one of the main reasons for high recurrence rate
follicular form
islands bordered by cells that resemble ameloblasts
tissue in middle of follicles is loose resembling stellate reticulum of tooth germ & can sometimes have cystic changes in follicle
management of ameloblastoma
- surgical resection with margin
- recurrence relatively common ~ 15%
- risk of malignant transformation <1% (ameloblastic carcinoma)
how would benign tumour appear in ultrasound (4)
well defined
encapsulated
peripheral vascularity
no lymphadenopathy
options for differential diagnosis for multilocular radiolucency in mandible
OKC
ameloblastoma
ameloblastic fibroma
odontogenic myxoma
odontogenic fibroma
follicular histopathology
tumour cells in follicular pattern
resemble enamel organ in developing tooth with a central mass resembling the stellate reticulum
surrounded by ameloblast like cells that display the typical reversed polarity, the nuclei are located away from the basement membrane opposite to what is usual
changes in the stellate area within the follicle
cystic breakdown - looks like large white spaces
squamous metaplasia
granular cell changes
plexiform histopathology
neoplastic epithelium arranged as a network of strands and irregular masses displaying the same cell layers as the follicular pattern with reversed polarity obvious
cyst degeneration in this type is mainly due to stromal degeneration
adenomatoid odontogenic tumour
benign epithelial tumour
3% of odontogenic tumours
most common 2nd decade
F>M
anterior maxilla
key about AOT
75% associated with u/e tooth, commonly maxillary canine
radiographic criteria of AOT
unilocular radiolucency
majority have internal calcification / radiopacities which increase as tumour matures
margins well defined & corticated
may displace adjacent structures but external root resorption rare
very similar to dentigerous cyst
difference between AOT & dentigerous cyst
AOT has
1. thicker cortical margins
2. attaches further down root (cyst attaches at CEJ)
histopathological criteria of AOT
epithelial in origin
arranged in duct like structures (big hole) described as rosette appearance
distinctive with patchy calcification
well developed fibrous tissue capsule surrounding cells so removal of tumour straightforward surgically & recurrence rate is LOW
calcifying epithelial odontogenic tumour
benign epithelial tumour
1% odontogenic tumours
most common 5th decade
M>F
posterior mandible most common
slow growing but can become large
1 in 2 associated with u/e tooth
radiographic criteria of CEOT
variable presentation
uni or multi locular
well or poorly defined margins
internal septa - poor / fine / none
odontogenic myxoma
mesenchymal benign tumour
3-6% of odontogenic tumours
most common in 3rd decade
F = M
Mandible > maxilla
radiographic criteria of odontogenic myxoma
well defined radiolucency +/- thin corticated margin
small lesions = unilocular
large lesions = multilocular
soap bubble appearance of septa
slow growth along bone before causing buccolingual expansion
scallops between teeth but larger lesions may cause displacement; external root resorption rare
histopathological criteria of odontogenic myxoma
loose myxoid tissue with stellate cells
may contain islands of inactive odontogenic epithelium
no capsule = locally invasive
odontogenic myxoma management
curettage / resection depending on size
high recurrence ~ 25%
follow up important
lower recurrence rate if unilocular
odontoma
benign mixed tumour
technically a hamartoma
malformation of dental tissue
1/5 - 2/3 of all odontogenic tumours
most common 2nd decade
F = M
odontoma similarities to teeth
mature to certain stage
can be associated with other odontogenic lesions e.g. dentigerous cyst
surrounded by dental follicle
lie above IAN canal
2 types of odontoma
complex -> disorganised mass of dental tissue, more common posterior body of mandible
compound -> ordered dental structures, may appear as multiple mini teeth, more common anterior maxilla
radiographic criteria of odontoma
well defined clump of radiopaque material
histopathological criteria of odontoma
both from mesenchymal & epithelial tissue
enamel is inorganic so is dissolved during process of slide development; may not show on slide dependent on level of calcification
ossifying fibroma clinical criteria
slow growing
wide age range
mainly mandible
similar to fibrous dysplasia but has capsule which is reflected in radiolucent line surrounding mass whereas dysplasia blends into the bone
histopathological criteria of ossifying fibroma
cellular fibrous tissue
immature bone
acellular calcifications
fibrous dysplasia
slow growing asymptomatic bony swelling due to bone being replaced by fibrous tissue
active u20yrs of age
can be single or multiple bone
maxilla > mandible
can be syndromic - albright’s syndrome (melanin pigment & early puberty)
radiographic criteria of fibrous dysplasia
margins often blend into adjacent bone
bone maintains approximate shape initially
becomes more radiopaque as lesion matures
can have variable appearances i.e. cotton wool / amorphous
histopathological criteria of fibrous dysplasia
fibro osseous
fibrous replacement of bone
no capsule separating it from normal bone
bone remodels and increases in density
rarefying osteitis
localised bone loss in response to inflammation
always occurring 2ndary to another form of pathology
if at apex of tooth consider apical periodontitis / PA granuloma / PA abscess
sclerosing osteitis
localised increase in bone density in response to low grade inflammation
most common around apex of tooth with necrotic pulp
PA radiopacity often poorly defined
may eventually lead to external root resorption if chronic
osteosarcoma
malignancy of bone
normally in 30s
if older generally due to paget’s
mandible > maxilla
recurrence, local destruction & metastases
paget’s disease
usually >40ys
M > F
aetiology unknown
serum biochemistry shows raised alkaline phosphatase
disease of disturbed bone turnover -> deposition & resorption occur at the same time so bone becomes soft & deformed then calcifies in deformed shape
dental changes with paget’s
loss of lamina dura
hypercementosis
migration (due to bone enlargement)
histology of paget’s
reversal lines - indicate change in turnover which can be very darkly stained
will burn out itself
osteoclastic & osteoblastic activity
tx of paget’s pt
xla of teeth can be difficult due to hypercementosis / pathological # of mandible / affected bone tends to develop osteosarcoma
dense bone harder to LA
MRONJ risk as on anti resorptives
osteosclerotic stage = less vascular so little bleeding so increased risk of dry socket / MRONJ
osteolytic stage = more vascular so lots of bleeding
