Bone lesions and cysts - radiology and histology Flashcards Preview

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How to describe a lesion on an x-ray (6)

radio density
effects on surrounding structures


What is the definition of a cyst

Pathological cavity filled w fluid, semi-fluid or gaseous contents.
Not filled with pus.
Has a wall, a lining (epithelium) and a lumen.


3 things/steps needed for a cyst to form

1. A source of epithelium
2. A stimulus for proliferation
3. Growth and bony resorption


Types of cysts in the jaws

Odontogenic cysts:
developmental (dentigerous cyst, eruption cyst, lateral periodontal cyst or odontogenic keratocyst)
Inflammatory (radicular cyst apical or lateral, residual cyst, paradental/collateral cyst)
Non-odontogenic cysts:
nasopalatal cyst
nasolabial cyst


How do cysts grow and proliferate

Breakdown in the centre of the cyst. This brings water into the cyst via osmosis which increases the hydrostatic pressure and makes the cyst grow + proliferation of the epithelium. Process continues.
Interleukin, cytokines drive this and activate Oc and cause bone resorption.


Radicular cyst epithelium source

Hertwigs root sheath/epithelial rests of Malassez in the PDL.


Stimulus for the formation of a radicular cyst

Chronic periapical inflammation/periapical periodontitis is replaced with granulation tissue to make a periapical granuloma.


location of radicular cyst

always associated w a non-vital tooth. Can be apical or lateral (lateral canals) or residual.


radiographic appearance of radicular cyst

well defined, corticated, large (15mm) radiolucency, continuous with the PDL


histological appearance of radicular cyst

non-keratinised epithelial lining, lots of chronic inflammatory cells.


how is a collateral/paradental cyst formed

stimulus is periodontal pocket inflammation and the cyst forms on the lateral aspect of the tooth.
Epithelium arises from the pocket epithelium.
Tooth needs to be at least partially erupted


histology of paradental cyst

attached at the ACJ and looks like a radicular cyst.


follicular cyst formation

cyst surrounding the crown of an unerupted tooth.
A developmental cyst
arises from the reduced enamel follicular epithelium.
Normal radiolucency around a developing tooth crown is 3mm (between the crown and the follicle)


dentigerous cysts + radiographic and histological features

Impacted tooth still in bone.
Well-defined, corticated radiolucency surrounding the crown and attaching at the ACJ.
Histologically = minimal inflammation, thin and regular non-keratinised epithelium


eruption cyst

a cyst surrounding the crown of an erupting tooth that is not in the bone.
Can impede the eruption of the tooth


how is an odontogenic keratocyst formed

arises from the dental lamina remnants.
Can be associated with an unerupted tooth, and in the 3rd molar region a lot of the time bc that's where you find remnants of dental lamina.


odontogenic keratocyst clinical/histological/ radiographic appearance

aggressive and infiltrative growth.
Fragile lining (thin parakeratinised, with the basal layer nuclei all standing in a line (nuclear palisading)). Fragile lining means bits get broken off when removal is attempted so has a high recurrence rate.
Can get daughter cysts which bud off and are easy to leave behind.
Cyst can be solid (filled w keratin if small).
radiographic = multi or unilocular, w smooth or irregular outlines and not much bucco-lingal expansion even if very large.


Odontogenic keratocyst associated syndrome

basal cell naevus/Gorlin-Goltz syndrome


what is gorlin-goltz syndrome

multiple, recurrent odontogenic keratocysts
multiple and recurrent basal cell carcinomas of skin not exposed to sun.
frontal bossing/wide forehead
calcified falx cerebri (midline in skull so transmits electrical signals more so more likely to get epilepsy)
wide set eyes
bifurcation in ribs


lateral periodontal cyst formation

Forms on the lateral aspect between vital teeth.
Epithelium arises from rests of Serres..


radiographic appearance of a lateral periodontal cyst

multilocular, well defined, corticated radiolucency.
Has localized thickenings of the lining (called plaques)


gingival cysts

can be in adults and in children.

In children:
- parakeratinised epithelium
- arises from dental lamina rests in the alveolar mucosa
- located under the alveolar mucosa

In adults:
- non-keratinised epithelium
- arises from dental lamina rests in the attached gingiva
- form in the attached gingivae


glandular odontogenic cysts

have cuboidal or columnar epithelium w mucus production, duct like/glandular structures.
High recurrence rate


calcifying odontogenic cyst

in young children.
radiolucency w calcification's.
lined with ameloblastoma-like epithelium and has ghost cells and dentine.


non-odontogenic cysts

nasopalatine cyst and nasolabial cysts


nasopalatine cyst formation

midline of anterior part of palate.
from nasopalatine duct epithelial residues as the processes fuse in utero.


nasopalatine cyst histological /clinical/radiographic appearance

lined by respiratory or mucosal epithelium or both.
can have nerve bundles or vascular signs in the lumen.
seen as a swelling in the hard palate.
radiographically it overlies the upper central incisors roots but is separate to them i.e. doesn't interfere or resorb them.


nasolabial cysts location

soft tissues of face - next to the nose, base of nostril or nasolabial fold


nasolabial cyst epithelium

remnants of nasolacrimal duct = pseudo-stratified columnar epithelium


what is an odontogenic tumour

tumour that arises from epithelium or mesenchyme. Radiolucent lesion, sometimes with calcifications.