Radiology Flashcards
What is a cyst?
a pathological cavity having fluid, semi-fluid or gaseous contents and which is not created by the accumulation of pus
Cysts - initial radiographs that can be taken to investigate
periapical
occlusal
panoramic
supplemental radiographs that can be taken to investigate cysts
CBCT
facial radiographs
Radiographic features of cysts
shape
- often spherical or egg-shaped
- most grow by hydrostatic pressure
margins
- often well defined
- often corticated
locularity
- ofren unilocular
multiplicity
- can be single, bilateral or multiple
- multiple cysts may indicate a syndrome
inclusion of unerupted teeth
Cysts - effect on surrounding anatomy
displacement of cortical plates, adjacent teeth, maxillary sinus, inferior alveolar canal
- variable degree and pattern of growth
- root resorption may occur with chronic cysts
cysts - radiographic signs of secondary infection
may lose definition and cortication
typically associated with clinical signs and symptoms
Classification of cysts
structure
- epithelium lined vs no epithelial lining
origin
- odontogenic vs non odontogenic
pathogenesis
- developmental vs inflammatory
give examples of developmental odontogenic cysts
dentigerous cyst and eruption cysts
odontogenic keratocyst
lateral periodontal cyst
give examples of odontogenic inflammatory cysts
radicular cyst and residual cyst
inflammatory collateral cysts
- paradental cyst
- buccal bifurcation cysts
features of odontogenic cysts
occur in tooth bearing areas
most common cause of bony swelling in the jaws
- >90% of all cysts in oral and maxillofacial region
all lined with epithelium
most common odontogenic cysts
radicular cyst (and residual cyst)
- 60% of odontogenic cysts
dentigerous cyst (and eruption cyst)
- 18%
odontogenic keratocyst
- 12%
radicular cysts features
inflammatory odontogenic cyst
- always associated with a non-vital tooth
- initiated by chronic inflammation at apex of tooth due to pulp necrosis
sometimes called dental cysts or periapical cysts
radicular cysts vs periapical granulomas
difficult to differentiate radiographically
radicular cysts typically larger
if radiolucency diameter >15mm = 2/3 cases will be radicular cysts
radicular cysts radiographic features
well defined, round/oval radiolucency
corticated margin continuous with lamina dura of non-vital tooth
larger lesions may cause displace adjacent structures
long-standing lesions may cause external root resorption and/or contain dystrophic calcification
radicular cyst histology
epithelial lining - often incomplete
connective tissue capsule
inflammation in capsule
how do radicular cysts grow?
osmotic effect with semi-permeable wall
cytokine mediated growth
name 2 variants of radicular cysts
residual cysts
lateral radicular cysts
what is a residual cyst?
when a radicular cyst persists after loss of tooth
- or after tooth is successfully root canal treated
what is a lateral radicular cyst?
a radicular cyst associated with an accessory canal
- located at side of tooth instead of apex
dentigerous cyst features
developmental odontogenic cyst
associated with crown of unerupted (and usually impacted) tooth
- e.g. mandibular 3rd molars, maxillary canines
cystic change of dental follicle
Dentigerous cyst radiological features
corticated margins attached to cemento-enamel junction of tooth
- larger cysts may begin to envelop root of tooth
may displace involved tooth
tend to be symmetrical initially
- larger cysts may begin to unilaterally expand
- variable displacement of cortical bone/bony expansion
dentigerous cyst - histology
thin non-keratinised stratified squamous epithelium
- may resemble radicular cyst if inflamed
how to tell the difference between a dentigerous cyst and an enlarged follicle
consider cyst if follicular space 5mm or more
- measure from surface of crown to edge of follicle
- normal follicular space typically 2-3mm
- assume cyst if >10mm
consider cyst if radiolucency is asymmetrical
eruption cyst features
variant of dentigerous cyst
- continued within soft tissue rather than bone
associated with an erupting tooth
- more commonly incisors
- almost exclusively affects children
odontogenic keratocyst radiographic features
often have scalloped margins
25% are multilocular
often cause displacement of adjacent teeth
- root resorption uncommon
characteristic expansion
- can have significant mesio-distal expansion without bucco-lingual expansion
nasopalatine duct cyst presentation
often asymptomatic
patients may note ‘salty’ discharge
larger cysts may displace teeth or cause swelling in palate
always involves midline but not always symmetrical
nasopalatine duct cyst; radiographic features
periapical or/and standard maxillary occlusal
- corticated radiolucency between/over roots of central incisors
- often unilocular
- may appear ‘heart shaped’ due to superimposition of anterior nasal spine
CBCT may be indicated if better visualisation of cyst required for surgical planning
Nasopalatine Cyst vs incisive fossa
incisive fossa
- may or may not be visible radiographically
- midline, oval shaped radiolucency
- typically not visibly corticated
transverse diameter can be considered in absence of clinical issues:
<6mm assume incisive fossa
6-10mm consider monitoring
>10mm = suspect cyst
Cysts - how to obtain material for histology
aspiration biopsy
- drainage of contents
incisional biopsy
- partial removal
excisional biopsy
- complete removal
incisional biopsy method for cysts
usually under LA
select region where lesion appears superficial
raise mucoperiosteal flap
remove bone as required
- using round bur
incise and remove section of lining
may be combined with marsupialisation
Cysts - outline surgical options
enucleation
- removal of all cystic lesion
marsupialisation
- creation of a surgical window in the wall of the cyst, removing the contents and suturing the cyst wall to the surrounding epithelium
- encourages the cyst to decrease in size and may be followed up by enucleation at a later date
enucleation is the treatment of choice for most cysts, what are the advantages?
whole lining can be examined pathologically
primary closure
little aftercare needed
enucleation disadvantages
risk of mandible fracture with very large cysts
for dentigerous cyst - may wish to preserve tooth
old age/ill health
clot filled cavity may become infected
incomplete removal of lining may lead to recurrence
damage to adjacent structures
marsupialisation indications
if enucleation would damage surrounding structures
- e.g. ID nerve
difficult access to area
may allow eruption of teeth affected by dentigerous cyst
elderly or medically compromised patient
very large cysts would risk jaw fracture if enucleation was performed
marsupialisation advantages
simple to perform
may spare vital structures
can combine with enucleation at later procedure
marsupialisation disadvantages
opening may close and cyst may reform
complete lining not available for histology
difficult to keep clean
lots of aftercare needed
long time to fill in
What is osteogenesis imperfecta?
aka - brittle bone disease
type 1 collagen defect
4 main types
clinical features of osteogenesis imperfecta
weak bones
multiple fracture
sometimes associated with type 1 dentinogenesis imperfecta
rarefying osteitis
localised loss of bone in response to inflammation
- occurs secondary to another from of pathology
condensing osteitis
localised increase in bone density in response to low-grade inflammation
- most common around apex of tooth with necrotic pulp
bone necrosis aetiology
osteomyelitis
- acute or chronic
avascular necrosis
- age related iscahemia
- anti-resorptive medication
irradiation
- ORN
Osteoclast inhibitors are commonly used to treat…
bone metastases
Paget’s disease
osteoporosis
Give examples of developmental bone abnormalities
Torus
- palatine
- mandibular
osteogenesis imperfecta
achondroplasia
- autosmal dominant
oseteopetrosis
- lack of osteoclast activity
fibrous dysplasia
- fibrous replacement of bone
- active under 20 years
- slow growing, asymptomatic bony swelling
Give 3 examples of metabolic bone diseases
osteoporosis
rickets and osteomalacia
hyperparathyroidism
What is osteoporosis
a quantitative deficiency of bone
bone atrophy as bone resorption exceeds formation
Osteoporosis aetiology
sex hormone status
calcium
physical activity
age
secondary
- hyperparathyroidism
- Cushing’s syndrome
- diabetes mellitus
Osteomalacia aetiology
vitamin D deficiency
- diet
- lack of sunlight
- renal causes
- malabsorption
osetiod forms but fails to calcify
what is hyperparathyroidism?
where calcium is mobilised from bones
Peripheral giant cell epulis - differential diagnosis
Brown’s tumour
aneurysmal bone cysts
giant cell tumours - very rare
Central giant cell granuloma
What is Cherubism?
a rare austominal dominant condition
multilocular lesions in multiple quadrants
Cherubism - histology
vascular giant cell lesions
Paget’s disease clinical signs
bone swelling
pain
nerve compression
Paget’s disease is linked to..
raised alkaline phosphatase
Paeget’s disease dental changes
Loss of lamina dura
hypercementosis
migration
- due to bone enlargement
Paget’s disease histology
active: increased bone turnover - osteoblast and osteoclast activity
will burn out
Paget’s complications
infection
tumour
What is an osetoma? describe the features
a bone tumour
- solitary
- mostly cortical bone
- slow growing
multiple osetomas can be indicative of…
Gardner syndrome
osetoblastoma - features
bone tumour
rare
often very active growth
Name 2 cementum lesions
cemetoblastoma
memento-osseous dysplasia
cementoblastoma features
neoplasm attached to root
histology same as osteoblastoma
osteosarcoma features
rare
age 30s - likely Paget’s related if elderly
mandible?maxilla
local destruction and bony expansion
risk of recurrence and metastases
Oodntogenic tumours classification
epithelial
mesenchymal
mixed
odotontogenic sources of epithelium
Rests of Malassez
- remnants of Hertwig’s epithelial root sheath
Rests of Serres
- remnants of dental lamina
reduced enamel epithelium
- remnants of the enamel organ
give examples of epithelial odontogenic tumours
ameloblastom a
adematoid odontogenic tumour
clarifying epithelial odontogenic tumour
name a mesenchymal odontogenic tumour
odontogenic myxoma
name a mixed odontogenic tumour
odontoma
> 50% of odontogenic tumours are..
ameloblastoma or odontoma
Ameloblastoma features
benign epitelial tumour
locally destructive but slow-growing
typically painless
80% in posterior mandible
odontoma features
benign mixed “tumour”
malformation of dental tissue
odontoma 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
types of odontoma
compound
- ordered dental structures
- may appear as denticles - multiple mini teeth
- more common in anterior maxilla
complex
- disorganised mass of dental tissues
- more common in posterior body of mandible
