RADIOLOGY cysts Flashcards
what causes radiolucency’s to appear on radiographs?
resorption of bone
decreased mineralisation of bone
decreased thickness of bone
why is it important to provide a provisional diagnosis from the radiographic appearance of a cyst/ cyst-like radiolucency?
to aid management
- indicates need/type of further investigation
- avoids unnecessary surgery
- prompts urgent management
what is a cyst?
a pathological cavity having fluid, semi-fluid or gaseous contents and which is not created by accumulation of pus
what is the meaning of indolent?
no harm to surrounding anatomy
what are the 2 categories of jaw cysts?
odontogenic (90%)
non-odontogenic
what are the 2 categories of odontogenic jaw cysts?
developmental
inflammatory
what are the types of developmental odontogenic jaw cysts?
dentigerous cyst (+ eruption cyst)
odontogenic keratocyst
lateral periodontal cyst
what are the types of inflammatory odontogenic jaw cysts?
radicular cyst (+residual cyst)
inflammatory collateral cysts (paradental and buccal bifurcation)
what is the common type of developmental non odontogenic jaw cyst?
nasopalatine duct cyst
what is a common difference seen on a radiograph when comparing OKC and ameloblastoma?
ameloblastoma causes displacement of cortices
what is the first step in differential diagnosis if any lesion?
is it anatomical?
is it artefactual?
is it pathological?
what are the 7 categories for describing radiolucency?
- site
- size
- shape
- margins
- internal structure
- effect on adjacent anatomy
- number
what can be noted when describing the site of a radiolucency?
where is it?
- alveolar bone vs basal bone
- where in the jaw
is there notable relationship to another structure?
- teeth (whole tooth, root, apex, follicle)
- IDC
- nasopalatine canal
what is its position relative to particular structures?
- IDC
- maxillary sinus floor
if a lesion sits below the IDC or entirely above the sinus floor, what’s it not likely to be?
odontogenic
how do you describe the size of a radiolucency?
measure (or estimate) dimensions
or
describe the boundaries
how do you describe the shape of a radiolucency?
locularity
- unilocular
- pseudolocular
- multilocular
general
- rounded
- scalloped
- irregular
how do you describe the margins of a radiolucency?
well defined and:
1. corticated
2. non corticated
poorly defined and:
3. blending into adjacent normal anatomy
4. ‘ragged’ or ‘moth-eaten’
what does a corticated radiolucency suggest?
benign lesion
what does a ‘moth-eaten’ radiolucency suggest?
malignancy
what does corticated mean?
a thin margin of bone surrounding radiolucency
what are the margins or cysts usually like?
well-defined and corticated
when may the margin of a cyst become poorly defined?
if infected
how would you describe the internal structure of a cyst like radiolucency?
- entirely radiolucent
- radiolucent with some internal radiopacity
- radiopaque
describe any internal radiopacities:
- amount (scant, multiple, dispersed)
- bony septae (thin/ coarse, prominent/ faint, straight/curved)
- particular structure (enamel and dentine radiodensity etc)
how do you describe tooth involvement with a cyst like radiolucency?
position:
- around apex/ apices
- at side of root
- around crown
- around entire tooth
what adjacent anatomy may be affected by cyst like radiolucencies?
teeth
bone
IDC/ max sinus/ nasal cavity
how may teeth be affected by radiolucency?
displacement/ impaction
resorption
loss of lamina dura
widening of PDL space
hypercementosis
how may bone be affected by radiolucencies?
displacement of cortices
perforation of cortices
sclerosis of trabecular bone
how may the IDC/ max sinus/ nasal cavity be affected by radiolucencies?
displaced
eroded
compressed
what may you suspect if there are multiple lesions?
a syndrome
what are potential causes of “periapical radiolucencies”?
periapical granuloma
periapical abscess
radicular cyst
perio-endo lesion
cemento-osseous dysplasia
surgical defect
fibrous healing defect
ameloblastoma occurring next to tooth
what other information is needed regarding a periapical radiolucency for diagnosis?
clinical symptoms and signs
condition of tooth, periodontal condition, tx history
patient demographic
what is the most common pathological radiolucency in the jaws?
radicular cyst (70%)
sometimes called “dental cyst” or “periapical cyst”
what initiates a radicular cyst?
chronic inflammation at the apex of a tooth due to pulp necrosis
*always associated with a non-vital tooth
what is the timeline of events from pulpal necrosis to a radicular cyst?
pulpal necrosis
periapical periodontitis
periapical granuloma
radicular cyst
radicular cyst presentation?
often asymptomatic
may become infected = pain
slow growing with limited expansion
what are the differences between radicular cysts and periapical granulomas?
difficult to differentiate radiographically
radicular cysts typically larger
if the radiolucency diameter >15mm = 2/3 cases will be a radicular cyst
what is the typical radiographic presentation of a radicular cyst?
site: apex of a non vital tooth
size: variable
shape: unilocular and rounded
margins: well-defined and corticated
internal structure: entirely radiolucent
tooth involvement: yes - associated with root; margins continuous with lamina dura
effects: can displace adjacent teeth/ structures; long standing lesions can cause external root resorption
number: single (potentially multiple if grossly carious dentition)
what procedure has a risk of devitalising a tooth?
crown prep
what are the variants of radicular cysts?
residual cyst
lateral radicular cyst
what is a residual cyst?
a radicular cyst persists after loss of tooth/ after a tooth is successfully RCTd
what is a lateral radicular cyst?
radicular cyst associated with an accessory canal
located at the side of tooth
what is a dentigerous cyst?
a developmental odontogenic cyst
how do dentigerous cysts arise?
cystic change of dental follicle
what teeth are dentigerous cysts associated with?
crowns of unerupted/ impacted teeth e.g., lower 8s and upper 3s
what is the incidence of dentigerous cysts?
second most common cyst (20%)
mandible >maxilla
what is the typical radiographic presentation of dentigerous cysts?
site: around the crown of unerupted tooth
size: variable
shape: unilocular and rounded but can be scalloped if large
margins: well-defined and corticated
internal structure: entirely radiolucent
tooth involvement: yes - continuous with CEJ (but large cysts can begin to envelope root as well)
effects: displacement of tooth; potential external root resorption of adjacent teeth; variable displacement of adjacent structures
number: single
in what circumstance would a radiolucent area around an impacted 8 be a considered a dentigerous cyst and not just normal?
if the follicular area is >5mm
or radiolucency is asymmetrical
in what circumstance would a radiolucent area around an impacted 8 be assumed a dentigerous cyst and not just normal?
> 10mm
what teeth are inflammatory collateral cysts associated with?
vital teeth
how many inflammatory collateral cysts present?
asymptomatic but can cause swelling
what are 2 subtypes of inflammatory collateral cysts?
buccal bifurcation cyst
paradental cyst
where may you find buccal bifurcation cysts?
typically occurs at buccal aspect of mandibular 1st molar
where may you find paradental cysts?
distal aspect of partially erupted mandibular 3rd molar
what is the typical radiographic presentation of inflammatory collateral cysts?
site: buccal/ distal to furcation area of permanent molar (mandible> maxilla)
size: <25mm
shape: unilocular and rounded
margins: well-defined and corticated
internal structure: entirely radiolucent
tooth involvement: yes - involves furcation
effects: tilting of tooth, cortical displacement
number or bilateral
what is an odontogenic keratocyst?
developmental odontogenic cyst with no specific relation to teeth
why are most OKCs large when noticed on radiograph?
they can grow large before clinically evident
incidence of OKC?
rare
mandible> maxilla
posterior> anterior
what were OKCs called until 2017?
keratocystic odontogenic tumour
what are typical radiographic presentations of OKC?
site: commonly posterior mandible
size: variable but can get very large
shape: pseudolocular or multilocular, scalloped
margins: well defined and corticated
internal structure: entirely radiolucent
tooth involvement: no (but often next to one)
effects: marked expansion within trabecular bone; minimal displacement of adjacent teeth
number: single (multiple if syndromic)
what syndrome presents with multiple OKCs?
basal cell naevus syndrome
what is the presentation of basal cell naevus syndrome?
multiple OKCs
multiple basal cell carcinomas on skin
palmar and plantar pitting
calcification of intracranial dura mater
what are the other names for basal cell naevus syndrome?
gorlin goltz syndrome
bifid rib syndrome
what is an ameloblastoma?
benign epithelial odontogenic tumour
locally destructive but slow growing
ameloblastoma presentation?
typically painless
locally destructive but slow growing
ameloblastoma incidence?
rare (but most common odontogenic tumour)
80% occur in posterior mandible
what are the types of ameloblastomas?
multicystic (85-90%)
unicystic; younger pts
histology of ameloblastoma?
follicular
plexiform
desmoplastic
what is the typical radiographic presentation of ameloblastoma?
site: common in posterior mandible
size: any size
shape: unilocular or multilocular (multilocular lesions may have course septae and/or soap bubble appearance
margins: well defined and corticated
internal structure: radiolucent (rare radiopaque variant)
effects: growth not constrained by cortices; thinning of cortices; can cause ‘knife edge’ external root resorption
number: single
what is an odontogenic myxoma?
benign mesenchymal odontogenic tumour
incidence of odontogenic myxoma?
rare
mandible> maxilla
what is the typical radiographic presentation of odontogenic myxoma?
site: often premolar/ molar region of mandible
size: any size
shape: multilocular and scalloped (may have coarse septae and/or soap bubble appearance, small lesions can be unilocular)
margins: well defined thin corticated margin
internal structure: radiolucent
tooth involvement: no
effects: initially extends into inter-radicular spaces but larger lesions displace teeth; initial expansion within trabecular bone before displacing cortices
number: single
what is a nasopalatine duct cyst?
developmental non odontogenic cyst
what do nasopalatine duct cysts arise from?
nasopalatine duct epithelial remnants
nasopalatine duct cyst presentation?
often asymptomatic
pt may notice ‘salty’ discharge
nasopalatine duct cyst incidence?
most common non-odontogenic cyst in jaws
affects 1% of population
what is another name for nasopalatine duct cyst?
incisive canal cyst
what is the typical radiographic presentation of nasopalatine duct cyst?
site: always anterior maxilla in midline
size: usually between 6-30mm in diameter
shape: unilocular, rounded and symmetrical (can be pseudolocular and lop sided, may appear heart shaped due to superimposed anterior nasal spine)
margins: well defined and corticated
internal structure: entirely radiolucent
tooth involvement: no, but inevitably next to incisor roots
effects: displacement of incisors, palatal expansion
number: single
how do you differentiate the incisive fossa from a cyst?
incisive fossa is in the midline and is an oval shaped radiolucency
it is typically not visibly corticated on radiographs
<6mm = assume incisive fossa
6-10mm = monitor
>10mm = suspect cyst
what is a solitary bone cyst?
non odontogenic lesion - technically not classed as a cyst
solitary bone cyst?
almost always no symptoms or clinical signs
other names for solitary bone cyst?
simple/ traumatic/ haemorrhagic bone cyst
incidence of solitary bone cyst?
rare
mandible> maxilla
can occur in association with other bone pathology e.g., fibro osseous lesions
typical radiographic presentation of solitary bone cyst?
site: typically posterior mandible
size: <30mm
shape: unilocular or pseudolocular, scalloped (may extend into inter radicular spaces with finger like projections)
margins: variable
internal structure: entirely radiolucent
tooth involvement: no
effects: typically none, rare displacement of teeth
number: single
what is stafne defect?
not a cyst but commonly mistaken as one
actually a depression in the bone - cortical bone preserved
contains salivary or fatty tissue
stafne defect presentation?
asymptomatic
stafne defect incidence?
rare
linked to salivary glands - mostly lingual mandible
stafne defect other name?
stafnes idiopathic bone cavity
typical radiographic presentation of stafnes defect?
site: mandible (often body)
size: <20mm
shape: unilocular and rounded
margins: well defined and corticated
internal structure: entirely radiolucent
tooth involvement: no
effects: typically none, rare displacement of adjacent structures
number: single
when infected cysts lose their well defined margins, how will you differentiate between a malignancy?
check for clinical features of 2nd infection:
pain
soft tissue swelling/ redness/ hotness
purulent exudate
when a radiolucency expands into the maxillary sinus, why does it become radiopaque?
lesion surrounded by air so appears radiopaque in comparison
