Cysts Flashcards
Define: cyst
Pathological cavity (usually epithelial lined) containing fluid, semi-fluid or gas that is not produced by the accumulation of pus
Describe the lining of cysts
- Continuous epithelial lining
- Discontinuous epithelial lining
- No epithelial lining
How do the majority of odontogenic cysts grow? What is the significance?
Hydrostatic mechanisms
Results in the round shape
How do OKC grow?
Through the medullary bone
What is required for a cyst to grow?
- Source of epithelium
- Proliferative stimulus
- Mechanism for growth
Define: odontogenic cyst
Cyst lined by epithelium dervied from odontogenic epithelium
Define: non-odontogenic cyst
Cyst lined by epithelium that is non-odontogenic in origin
Define: Inflammatory cyst
Inflammation is the stimulus causing epithelial proliferation and cyst formation
Define: developmental cyst
Where aetiology is unknown and deemed developmental
Epithelial source for radicular and residual cysts
Cell rests of Malassez
Epithelial source for dentigerous cysts and eruption cysts
Reduced enamel epithelium
Epithelial source for OKC, lateral periodontal cyst
Cell rests of Serres (remnants of the dental lamina)
List the odontogenic developmental cysts
OKC Dentigerous cyst Lateral periodontal cyst Eruption cyst Glandular odontogenic cyst Gingival cyst
List the odontogenic inflammatory cysts
Radicular cyst
Residual cyst
Paradental cyst
Which cysts are non-odontogenic?
Nasopalatine
Nasolabial
Presentation of cysts
- Compressible swelling if large
- Displacement or loose teeth
- If infected - similar symptoms to abscess (pain, discharge)
How does swelling occur with cysts?
Cyst expands through the normal anatomical boundaries of bone
Where is the swelling of cysts usually located?
Buccal or palatal in maxilla
Buccal in mandible (rare in lingual as it is thicker than buccal)
What are the characteristic clinical signs of cysts
- Eggshell cracking
- Bluish colour of mucosa
- Fluctuation
- Discharge of colourless fluid (cholesterol crystals)
What is eggshell cracking? How does it occur?
Continued resorption and bony expansion results in a thin layer of bone around the cyst which is easily broken on palpation
What is fluctuation?
Pushing the swelling on one side and feeling the transmission of pressure on the other side
What does fluctuation indicate?
The lesion is fluid filled
What proportion of patients with cysts have no symptoms
1/3 are asymptomatic and found by chance on radiograph
How may a cyst be detected during rct?
Inability to dry canals with paper points, could be due to cholesterol clefts indicating a cyst
List the investigations for cysts
Vitality testing of nearby teeth
Radiographs
Biopsies to confirm diagnosis
Aspiration?
List the histological features of INFLAMMATORY cysts
- Non-keratinised stratified epithelial lining
- Thick fibrous wall
- Inflammation markers present
- Cholesterol clefts
- Hyaline bodies
How do cysts resorb bone?
- The cyst itself does not resorb, instead the cyst/inflammatory mediators induces osteoclast activation
How fast do cysts grow on average?
Slow - 2cm in 10 years
How fast do cysts grow in children and why?
Faster - 5cm in 2 years
Due to less dense bone and quicker turnover
Frequency of radicular cysts
70%
Frequency of dentigerous cysts
15-20%
Frequency of OKC
3-5%
Define radicular cyst
Inflammatory cyst that develops from cell rest of Malassez stimulated to proliferate via inflammatory process arising from pulpal necrosis
Describe the lining of radicular cysts
Non-keratinised, squamous epithelium
May be discontinuous if replaced by granulation tissue or mural cholesterol nodules
What histological features are associated with radicular cysts
- Acute and chronic inflammatory cells
- Cholesterol clefts
- Foamy macrophages
- Hemosiderin
- Rushton’s bodies
Where are radicular cysts commonly found
Apex of non-vital tooth
Upper laterals common
Anterior maxilla > mandible
Describe the radiographic appearance of radicular cysts
- Size - 1.5-3cm dia
- Shape - round, unilocular
- Outline - smooth, well corticated if long standing and may be continous with lamina dura
- Uniformy radiolucent
What effects do radicular cysts and residual cysts have on adjacent structures
Displaced adjacent teeth (Rarely resorbed)
Buccal expansion
Displacement of antrum
Difference between the radiographic appearance of radicular cysts and apical granuloma
- Cysts have corticated margins, whereas granuloma does not
Define a residual radicular cyst
Remnant of a radicular cyst after the causative tooth has been extracted
How do residual cysts grow?
Via osmotic pressure - however it is very low as the tooth is not there
Where are residual cysts found?
Apical regions of an edentulous area in a tooth bearing region
Usually mandibular premolar area
Describe radiographic appearance of residual cysts
- Size - 2-3mm dia
- Shape - round, unilocular
- Outline - smooth, well-defined and well corticated margins
- Uniformly radiolucent
Define dentigerous cysts
Cyst developing from the remnants of the reduced enamel epithelium after the tooth has formed
What features does a cyst need in order to be dentigerous?
- Must contain the crown of the unerupted tooth
- Epithelial lining of the cyst is attached to the CEJ of the unerupted tooth
Describe the lining of dentigerous cysts
Cuboidal or squmous epithelial lining
May have mucous cells or focal areas of keratinisation of superficial layers
Where are dentigerous cysts found?
Associated with the crown of unerupted and/or displaced tooth - classically 3s, 5s or 8s
Describe the radiographic appearance of a dentigerous cysts
- Size - variable - can be small or can extend up the ramus
- Shape - round or oval, unilocular, typically envelops crown symmetrically
- Uniformly radiolucent
Effects of dentigerous cysts
- Associated tooth unerupted and idsplaced
- Adj eeth displaced, resorbed or enveloped
- Buccal and mesial expansion
- Displace antrum and ID canal
What is a false dentigerous relationship
Large cysts that envelop a tooth may be mistaken for dentigerous cysts
Define odontogenic keratocyst
Cyst arising from the cell rest of Serres due to traumatic implantaion of down growth of the basal cell layer of surface epithelium or REE of the dental follicle
What is the difficulty of treating mulilocular cysts e.g. OKC?
They have a tendency to recur
Describe the lining of OKC
Continuous and even layer of keratinised stratified squamous epithelium
Often parakeratinised, but sometimes orthokeratinised
Describe the basal cell layer in OKC
Well defined with cuboidal or columnar cells displaying palisading
What is the lumen of OKC filled with
Shed squames and fibrous tissue in the capsule
How can characteristic features be lost in OKC
Due to inflammation
Where are OKC found?
Posterior border/angle of the mandible (where 8s are)
May occur in anterior maxilla
Why are OKC found posterior mandible
8s are the last teeth to erupt therefore this is where the cell rests remain
Describe the radiographic appearance of OKC
Size - varies, can become extensive
- Shape - oval, extends along body of mandible and can be unilocular, multilocualr or pseudolocular
- Outline - smooth if unilocular, scalloped if multilocular, corticated and can be well or poorly defined
How is multilocularity determined
Bony septa between the locules
Describe the effects of OKC
- Minimal displacement and rarely resorbs adj teeth
- Extensive expansion within cancellous bone (not lingual or buccal)
- Cortical perforation
- May envelop crowns of lower 8s (false dentigerous)
How do OKC grow
Via high mitotic activity in the lining which secretes bone resorbing factors, thus burrowing it along the path of least resistance
What is the growth of OKC similar to
Ameloblastoma and giant cell lesion
Differentiating between OKC and ameloblastoma
Ameloblastoma can dispalce, resorb teeth and expand jaw - OKC does not
Define the aetiology of basal cell naevus syndrome (Gorlins)
Autosomal dominant or sporadic mutation of the patched gene
What is the significance of the patched gene
Developmental patterning of face and skeleton
Tumour suppression via hedgehog signalling pathway
Clinical features of basal cell naevus syndrome
- Multiple OKC
- Multiple basal cell carcinomas that may ulcerate
- Bifid, fused and supernumerary ribs
- Frontal bossing
- Skeletal class 3
Describe lateral periodontal cyst
Cyst in the periodontal region that is not inflammatory or an atypical OKC
How can biopsy confirm lateral periodontal cyst
Two plauqes/thickenings in the epithelial lining
Where are lateral periodontal cysts located
Lateral surface of the roots of vital teeth
Usually lower canine/premolar or upper laterals
Describe radiographic appearance of lateral periodontal cysts
- Small <1mm
- Shape - unilocular, round
- Outline - smooth, well defined and corticated
- Uniformly radiolucent
What are the effects of lateral periodontal cyst
If large, it can displace adjacent teeth
Buccal expansion
Tooth remains vital
Define botryoid odontogenic cyst
They are the multilocular variant of lateral periodontal cyst
Define paradental cyst
Inflammatory cyst arising from the epithelium near the furcation of molars often due to pericoronitis/inflammation
What are paradental cysts also called
Inflammatory collateral cysts
Describe nasopalatine cysts
Most common non-odontogenic cyst, it is developmental in origin and arises from epithelium in the incisive canal
What may a pt with nasopalatine cyst present with
Swelling palatally over incisive canal
Discharge into nose or mouth
Describe the radiographic appearance of nasopalatine cysts
Midline
Shape - round OR heart shaped due to superimposition of anterior nasal spine
Outline - well defined
Radiolucent
Where are nasopalatine cysts found
In the midline of the anterior maxilla
Effects of nasopalatine cysts
May displaced teeth if it is large
Describe the lining of nasopalatine cysts
Pseudostratified columnar epithelium (Respiratory epi) or stratified squamous
Describe nasolabial cysts
Non-odontogenic, soft tissue cyst arising in the nasolabial fold, upper buccal sulcus or lip
Effects of nasolabial cyst
May erode bone of the anterior nasal apeture
Lining of nasolabial cysts
Non-ciliated pseudostratified columnar, often rich in mucous cells (resp epithelium)
When to biopsy a cyst
- if the appearance is atypical for a cyst to confirm a diagnosis
- If concerns of tumour or multilocular lesion that is likely to recur
- Excisional biopsy as a definitive tx
What may be aspirated out a cyst?
- Clear/straw coloured fluid that shimmers = cholesterol crystals
- Creamy viscous fluid = keratin therefore OKC
- Creamy pus if infected
What does tx of a cyst depend on?
- Type of cyst
- Presence of infection
- Recurrence risk
- Neoplastic change rate
- Number of cysts present
- Structures associated e.g. nerves, vessles, antrum
Define enucleation
Removal of entire cyst (epi layer and capsular layer) from the bony cavity to ensure no pathological tissue remains
Describe enucleation procedure
Large mucoperiosteal flap raised
Cyst peeled off bony cavity
Flush area with saline and suture
Specimen sent to lab for diagnosis
Describe marsupialisation/decompression procedure
- Window cut into soft tissue overlying cyst
- Inner epithelium is sutured to outer epithelium
- Cyst lining sutured to oral mucosa to keep it open
- BIPP used to fill the cavity to prevent food accumulation
Aims of marsupialisation
Reduce size of the cyst to relieve pressure via bone deposition at the base of the cavity
Indications for marsupialisation
Large cyst whereby there is a risk of jaw fracture if eneculation is carried out
Associated structures at risk if enucleation carried out
What is BIPP
Bismuth iodoform paraffin paste
What may follow marsupialisation
Enucleation of the remaining cyst
What are the types of excisions
Wide local excision
En bloc excision
What is wide local excision
Removal of lesion with a margin of normal bone
What is en bloc resection
Removal of a portion of a structure with a tumour
Tx options for radicular cyst
- RCT alone
- RCT and enucleate
- RCT, apicectomy, retrograde root filling and enucleation
- extraction and enucleation
Indications for rct alone for radicular cyst tx
Small radicular cysts only
Review of pts after tx for radicular cysts
Low recurrence rate but monitor 3 months and 6 months for bony infill
Tx of residual cysts
- Enucleation very effective without risk of recurrence
Tx of dentigerous cyst
Marsupialsation
May be followed by enucleation or excision
Tx of nasopalatine cyst
- Enucleation via palatal approach has a low recurrence rate
What is sacrificed in nasoplatine cyst enucleation
The incisive nerve
Tx of OKC
- Enucleation with chemical fixative +/- peripheral ostectomy
- Excision / resection
- Marsupialisation
Risk of simple enucleation with OKC
High recurrence due to satellite cysts within the fibrous wall and cancellous bone
What does chemical fixative do
Necrosis of remnants
It hardens the cyst making it easier to remove
Give an example of chemical fixative
Carnoy’s solution
What tx options for OKC have the best results
- Resection
- Enucleation, peripheral osteotomy and carnoy’s solution
What is peripheral ostectomy
Drilling peripheral bone
Monitoring of OKC
3/6/12 then annually
Tx of lateral periodontal cyst
Buccal flap raised
Cutterage/enucleation
Remains tooth vitality
Suspicious signs indicating tumour (not a cyst)
- Recent onset of symptoms
- Fast growing
- Neuropathy
- Resorption of adjacent structures
- Lack of response to antibiotics or RCT
