Cysts of the Jaw and Other Orofacial Tissues Flashcards
Define a cyst
A pathological epithelial lined cavity within tissue that can be filled with fluid or gas (not created by the formation of pus)
How do we classify cysts?
Cysts are classified into:
Hard tissue cysts
Soft tissue cysts
Hard tissue cysts are further divided into:
Odontogenic cysts (arising from the tooth or tooth forming structures)
Non-odontogenic cysts (arising from the fusion of plates, processes or the premaxilla during embryological development of the face)
Non-epithelial lined cysts (present like cysts but are not truly cysts as they are not epithelial lined cavities)
Soft tissue cysts are further divided into:
Developmental cysts
Non-developmental cysts
Briefly describe why cysts can form
Epithelium is a particular kind of tissue that is found on lining surfaces. Its nature means that it tends to try and cover things or exclude material from the body. This includes pathological cavities. When these pathological cavities become lined with epithelium, they become a cyst
Why are some non-epithelialised cavities called cysts?
Although they are not true cysts, they present like cysts clinically and radiographically. We would not be able to determine that they are not cysts until we treat them and send them to histopathology
Briefly describe the category of odontogenic cysts
A pathological epithelial lined cavity arising from the tooth forming tissues (epithelial cell rests, enamel follicle, enamel organ, dental lamina etc.)
There are many types, some of which are inflammatory (radicular cysts, residual cysts, paradental cysts) and some of which are non-inflammatory (dentigerous, keratocysts, lateral periodontal, calcifying odontogenic cyst, glandular odontogenic cyst)
Odontogenic cysts can be classified into:
Inflammatory and non-inflammatory odontogenic cysts-
Inflammatory-
PA/radicular
Residual
Paradental
Non-inflammatory (developmental)-
Dentigerous
Keratocyst
Lateral periodontal
Calcifying odontogenic cyst
Glandular odontogenic cyst
Describe the epidemiology of odontogenic cysts
Generally, very common.
70% of all odontogenic cysts will be radicular/PA cysts
15% of all odontogenic cysts will be dentigerous cysts
10% of all odontogenic cysts will be keratocysts
5% of all odontogenic cysts will encompass all other cyst forms
Generally, how do cysts present?
Usually asymptomatic incidental findings on radiographs
Can be associated with movement or migration of teeth/other structures or failed eruption of teeth
May cause swellings that happen slowly over the course of months to years
Can become infected, in which case, they will cause pain and swelling (symptomatic).
If cysts in the lower jaw become large enough, they may be obstruct the function of the inferior alveolar nerve, leading to numbness in its distribution (lower lip, chin, teeth on affected side)
Typically well-defined, corticated radiolucencies
May be unilocular (single circular cyst) or multilocular (multiple locules within the cavity, with thin bony septa separating each of them from one another)
Why are cysts a problem?
Although, they’re asymptomatic, cysts can grow, having the potential to move, loosen or damage teeth as well as other anatomical structures e.g., inferior alveolar nerve
If they get big enough, they may come close to the surface which can cause them to become infected and therefore symptomatic
If they get big enough, they can weaken the bone, leading to potential pathological fracture. This will occur at a very late stage of cyst development
As the cyst gets bigger, their treatment becomes much more complex and difficult to undertake. Therefore, they should be removed as soon as discovered, when they are much smaller
Briefly describe the pathophysiology of a radicular cyst
Also known as a PA cyst
A carious tooth with a pulp that has died off due to caries progression will eventually result in chronic inflammation at the apex of the tooth
This inflammation causes proliferation of a number of cells around the apex of the tooth, including epithelial cells and cell rests of Malassez within the PDL. These expand to form a ball.
Initially, this radiolucency can represent a PA granuloma which is essentially a cavity containing epithelial cells, WBCs and debris.
If the granuloma persists because the tooth isn’t removed or doesn’t undergo RCT, we get central liquefaction and necrosis of the cells, leaving only epithelial cells around the outside of the cyst cavity. It is at this point the granuloma transforms into a PA cyst.
How do radicular cysts present radiographically?
A well-defined, corticated, unilocular radiolucency almost always around the apex of a non-vital tooth.
May see evidence of non-vitality through deep caries (caries progression into the pulpal space), large restorations, RCT’d/crowned tooth, history of trauma to the tooth.
What is a residual cyst?
If there was a tooth with an associated PA cyst that has now been removed without the removal of the cyst (has not been treated with enucleation etc.), the cyst may persist and as a result, we end up with a residual cyst.
Often seen underneath bridges
Briefly describe the pathophysiology of a dentigerous cyst
Non-inflammatory, developmental cyst
As the crown of a tooth is completed and the enamel is laid down, the enamel follicle sits over it. This is the remnant of the enamel organ.
If the tooth doesn’t erupt, then some fluid can get caught between the enamel surface and the enamel follicle. This can start to expand and form a dentigerous cyst.
List the features of a dentigerous cyst
Will be associated with the crown of an unerupted tooth. Will envelope the crown into the cavity.
The cyst will almost always end at the junction between the crown and the root (ACJ)
May displace/push the associated unerupted tooth
May cause resorption of other teeth/damage adjacent teeth
What is the specific rationale to remove a dentigerous cyst with the associated unerupted tooth?
Want to eliminate the risk of displacing the unerupted tooth or damaging adjacent teeth (root resorption)
Why do dentigerous cysts tend to almost always stop at the ACJ?
As this cyst type tends to be associated with the crown of an unerupted tooth, they tend to be limited by the ACJ (limit of the enamel at the neck of the tooth, just before it starts to form the root).
This is where the dental follicle is attached and so it makes sense that as the dental follicle expands, the edges of it will remain attached to the ACJ. As a result, a dentigerous cyst tends to almost always appear to stop at the ACJ.
But not always, can envelope the tooth much more extensively if the cyst is able to get big enough.
What tooth forming structure does an odontogenic keratocyst arise from?
Dental lamina
What tooth forming structure does a radicular cyst arise from?
Epithelial cell tests of Malassez within the PDL
What tooth forming structure does a residual cyst arise from?
Epithelial cell rests of Malassez within the PDL
What tooth forming structure does a dentigerous cyst arise from?
Enamel follicle
What tooth forming structure does a lateral periodontal cyst arise from?
Unknown, could be the enamel follicle or dental lamina
Some even propose it is the epithelial cell rests of Malassez within the PDL
Which cyst has the highest recurrence rate and is the most difficult to treat out of all odontogenic cysts?
Odontogenic keratocysts
Why do odontogenic keratocysts have a high recurrence rate?
These cysts are very difficult to treat because they tend to have multiple locules and so it becomes easy to miss one locule during enucleation and not remove the entire cystic tissue.
To add, the cyst lining tends to be very delicate and friable, therefore it is very easy to leave some cystic tissue behind
The residual cystic tissue that is left behind, then has a chance to persist and continue to grow
List the features of an odontogenic keratocyst
Likely a well defined, corticated multilocular (rather than unilocular) radiolucency
Affects the mandible more than the maxilla, but can be seen in both
Can present anywhere but most commonly seen in the angle of the mandible around where the wisdom tooth should be (50%)
May be associated with an unerupted tooth
Can be quite extensive but tend to cause minimal expansion and therefore we don’t tend to see a lot of swelling (will require the cyst to erode through the ramus and the body of the mandible before causing expansion/swelling)
Can damage adjacent teeth
If a patient presents with multiple odontogenic keratocysts to your clinic, what should you suspect?
Consider the possibility the patient may have undiagnosed Gorlin Goltz syndrome
Assess patient for features of the syndrome such as facial bossing (prominent forehead), hypertelorism (wide inter-eye distance), multiple basal cell naevi on the skin, skeletal abnormalities
Refer patient to GP for definitive diagnosis, if suspected
Gorlin Goltz syndrome is associated with which odontogenic cyst?
Odontogenic kerayocysts
List the features of Gorlin Goltz syndrome
Multiple odontogenic keratocysts
Skeletal abnormalities
Facial bossing (prominent forehead)
Multiple basal cell naevi
Hypertelorism (wide inter-eye distance)
Where are we most likely to find an odontogenic keratocyst?
Mandible>maxilla
Angle of the mandible
Briefly describe the features of an eruption cyst
Associated with erupting teeth, often considered a superficial dentigerous cyst
Occurs in kids, just as a tooth is about to erupt
Swelling tends to take a bluish shade and appear round. Located where we expect a tooth to erupt
Most self-resolve, rupturing spontaneously as the tooth underlying them erupts and becomes exposed
Will not see a radiolucency outside the bone
How is an eruption cyst treated?
Most self-resolve, rupturing spontaneously as the tooth underlying them erupts and becomes exposed.
Therefore tend to not need any active intervention unless the cyst is causing symptoms, in which case an incision may be made to de-roof the cyst
Briefly describe the pathophysiology of an eruption cyst
The enamel follicle that has been assisting the tooth in its eruption process forms a cyst.
Essentially, a superficial dentigerous cyst
List the features of a lateral periodontal cyst
Non-inflammatory, developmental cyst
Well-defined, corticated, unilocular radiolucency associated with a vital tooth
Located mesial or distal to the associated tooth (at the side), between the ACJ and the apex of the tooth
Tear-drop shaped. As there is more space between the apices of the teeth then there is at the crown margin, the cyst appears slightly wider in the direction of the apex, resulting in this shape
What is the botryoid variant?
Multilocular variant of a lateral periodontal cyst
Well defined multilocular radiolucency located at the side of a tooth, between the ACJ and the apex
Has a tear drop shape
List the features of a glandular odontogenic cyst
Rare non-inflammatory, developmental cyst. But display variable behaviour, so some argue they are not cysts but low grade tumours
May be found in association with odontogenic keratocysts, ameloblastomas or other pathology
Well-defined, corticated, unilocular radiolucency that presents like other cysts
May be associated with non-vital teeth or unerupted teeth and therefore mistaken for radicular or dentigerous cysts
Contain some cuboidal glandular cells. Only able to determine this through histopathology, otherwise present like other cysts and may be mistaken for them
Recurrence more likely
List the features of a calcifying odontogenic cyst
Rare non-inflammatory, developmental cyst. But display variable behaviour, so some argue they are not cysts but low grade tumours
May be found in association with odontogenic keratocysts, ameloblastomas or other pathology
Well-defined, corticated, unilocular radiolucency that presents like other cysts
Contain areas of calcification or odontoma formation within them (radiopacities within the larger radiolicency)
Recurrence more likely
A well-defined, corticated unilocular radiolucency that appears to be associated with the crown of an unerupted wisdom tooth is seen on an OPT. List the differential diagnoses for this presentation and how you would reach the definitive diagnosis in this scenario.
Dentigerous cyst
Glandular odontogenic cyst
Odontogenic keratocyst (although these tend to rarely present as unilocular radiolucencies)
Only way to determine which cyst type this is to remove the cyst and send it to histopathology.
A histopathologist will conduct a histological exam to determine the cells within the cyst. If glandular epithelium is observed, this would mean the cyst is a glandular odontogenic cyst as opposed to the other forms who will have their own histological markers of differentiation
List some non-odontogenic hard tissue cysts
Nasopalatine duct cyst
Globulomaxillary cyst
Median palatal cyst
How do non-odontogenic hard tissue cysts form?
These cysts are developmental cysts but do not arise from tooth forming tissues.
Instead, they arise during the embryological development of the face due to the fusion of different hard tissue structures such as the palatal plates, processes and premaxilla.
As these structures fuse, we get lines of fusion. Where these lines of fusions form, we can get inclusion of the epithelium which can go on to form a cyst in the future
How does a naso-palatine duct cyst arise?
Developmental, non-odontogenic cyst that arises from the fusion of hard tissue structures (fusion of 2 lateral palatal structures and the premaxilla at the front).
As these structures fuse, a line of fusion forms. Where this line of fusion forms, we can get an inclusion of the epithelium which can go on to form a cyst in the future
How does a globulomaxillary cyst arise?
Developmental, non-odontogenic cyst that arises from the fusion of hard tissue structures (fusion of the premaxilla and the maxillary plates)
As these structures fuse, a line of fusion forms. Where this line of fusion forms, we can get an inclusion of the epithelium which can go on to form a cyst in the future
These cysts tend to be between the upper 2 and 3
How does a median palatal cyst arise?
Developmental, non-odontogenic cyst that arises from the fusion of hard tissue structures (fusion of the palatal shelves)
As these structures fuse, a line of fusion forms. Where this line of fusion forms, we can get an inclusion of the epithelium which can go on to form a cyst in the future
Describe the features of a nasopalatine duct cyst
Painless swelling on the hard palate, located behind the central incisors
On a radiograph, will present as a well defined, corticated, unilocular radiolucency between and slightly beyond the upper incisors
May cause displacement of the upper incisors
Describe the features of a globulomaxillary cyst
Painless swelling on the buccal surfaces, often between the upper 2 and 3
On a radiograph, will present as a well defined, corticated, unilocular radiolucency
May cause displacement of the associated teeth
Describe the features of a median palatal cyst
Painless swelling located on the hard palate
On a radiograph (upper occlusal), will present as a well defined, corticated, unilocular radiolucency located on the hard palate behind the central incisors (at a distance from them)
What are non-epithelialised cysts? List some examples
Called cysts but are not actually cysts as they are not epithelial lined (but are cavities). Just present like cysts clinically and radiographically.
Staphne’s idiopathic bone cavity
Solitary bone cyst (also known as a traumatic bone cyst or a unicameral cyst)
Aneurysmal bone cyst
How does a Staphne’s idiopathic bone cavity arise?
Essentially, an inclusion of normal submandibular gland tissue in the lingual aspect of the mandible
Requires no treatment
How does a Staphne’s idiopathic bone cavity present on a radiograph?
Well defined, corticated, unilocular radiolucency
Located underneath the ID canal, not associated with the apex of a tooth or the crown of an unerupted tooth
How does a Staphne’s idiopathic bone cavity present on a CT scan?
Indentation of the lingual aspect of the mandible
Describe the features of a solitary bone cyst
Non-odontogenic, non-epithelial lined cavity
Patient may report a history of trauma in the area during childhood
On a radiograph, we will see a well defined unilocular radiolucency with no expansion or movement of associated teeth/adjacent structures
If they are opened, we will often see a fibrous tissue or endothelial lining. Won’t see much in the tissue, just some blood and a very thin lining which comes away quite easily.
How are solitary bone cysts treated?
Cyst is opened up and a biopsy is taken from the cyst and sent to histopathology
Undergoes curettage and is then enucleated which tends to resolve it
Describe the features of an aneurysmal bone cyst
Very rare, non-odontogenic, non-epithelial lined cavity, filled with blood
On a radiograph, will present as a moderately defined, corticated radiolucency with a soap bubble appearance and faint trabeculation within it (pseudolocular appearance)
Expansile lesion (balloon like)
On histological examination, we will see a cavity with a fibrous lining which is filled with blood
Soft tissue cysts can be divided into:
Developmental
Non-developmental
How do developmental soft tissue cysts arise? List some examples
As the fusion of the branchial arches and closure of the branchial cleft occur, we can get the inclusion of epithelium and epithelial structures (essentially get caught up in the process). This leads to the formation of developmental soft tissue cysts.
Dermoid cysts
Branchial cleft cysts
Thyroglossal duct cysts
Describe the features of a dermoid cyst
Most common, developmental, soft tissue cyst in the head and neck. Caused by the inclusion of epithelium and epithelial structures as the midline and the soft tissue overlying it fuses (formed due to the fusion of branchial arches)
Tend to present as a sublingual swelling
Tend to be round, located in the lower midline behind the teeth in the FoM
Presents as a fairly robust bag of keratinised epithelium which very often contain hair and sweat glands (because of the nature of the tissue that forms them)
Describe the features of a branchial cleft cyst
Can present as little round swellings around the neck region
In adults, they can present as fairly large neck swellings
How do brancial cleft sinuses arise?
Sinuses are one ended openings which are epithelial lined. Formed from the closure of branchial clefts.
Very common in the structures that are formed by the 1/2/3rd branchial arches (mandible, part of the ear and the hyoid bone).
Describe the features of a branchial cleft sinus
A swelling/lump with a central opening on the skin of the face/neck. Tend to develop below the chin/collarbone/neck.
Can fill up with fluid, tissue or discharge
Quite common in children
Don’t usually cause problems, just cosmetically problematic.
How are branchial cleft sinuses different from branchial cleft cysts?
Although both are formed from the closure of branchial clefts, sinuses are one ended openings which are epithelial lined. A cyst is completely enclosed within the tissues, a sinus will have an opening that goes on to the surface.
How do thryoglossal duct cysts arise?
The thyroid actually develops from tissues that originate in the foramen cecum (which is part of the posterior tongue, where the back of the anterior 2/3rds of the tongue and the junction with the posterior 1/3rd of the tongue are). This migrates down into the neck to form the thyroid tissues.
During this process, we can get a little bit of epithelial tissue caught along the way, which fails to move and can later on in life, form a midline thyroglossal duct cyst.
Describe the features of a thryoglossal duct cyst
A swelling/lump in the midline of the neck, just below the chin
List some non-developmental soft tissue cysts
Non-developmental soft tissue cysts tend to be associated with salivary gland tissue. Examples include-
Ranulas
Mucoceles
Non-developmental soft tissue cysts tend to be associated with salivary gland tissues and can be divided into 2 sub-types. What are these sub-types?
Mucous retention cysts-
Blockage of saliva/mucous within the salivary gland or duct
Involves minor salivary glands
Mucous extravasation cysts-
Escape of saliva from traumatised salivary gland or duct
Involves minor salivary glands or sublingual salivary gland
How does a mucous retention cyst arise?
Saliva and mucous get caught up within the salivary gland/duct causing an obstruction or blockage within it which causes the salivary gland/duct to swell up
Tend to form in minor salivary glands
How does a mucous extravasation cyst arise?
Saliva escapes from a traumatised salivary gland/duct. Once the saliva gets out of the gland/duct that they are supposed to be contained by, the nature of epithelium allows the epithelium to migrate around the bag of escaped saliva to form an epithelial cyst lining.
Tends to involve minor salivary glands or the sublingual gland.
Describe the features of a ranula
Non-developmental soft tissue cyst
Mucous extravasation cyst that forms on the floor of the mouth and involves either the minor salivary glands or sublingual gland.
Will present as a swelling in the FoM
How does a ranula arise?
Essentially, a mucous extravasation cyst, so saliva escapes from the minor salivary glands or the sublingual salivary glands into the tissues (often following trauma to these areas).
Here, the epithelium will migrate around the escaped saliva, forming an epithelial lining
Describe the features of a plunging ranula
Non-developmental soft tissue cyst
Mucous extravasation cyst that forms on the floor of the mouth and involves either the minor salivary glands or sublingual gland
Extends through the mylohyoid muscle to cause a neck swelling as well as a swelling in the FoM. This is because of a developmental defect in the mylohyoid muscle (hole in the muscle) which the ranula can squeeze through, giving a swelling that is partly in the mouth and partly in the neck
A ranula is normally treated using IO excision. How does the treatment for a plunging ranula differ and why?
A plunging ranula presents as a swelling in the floor of the mouth but also in the neck.
This is because of a developmental defect in the mylohyoid muscle (hole in the muscle) which the ranula can squeeze through, to give a cystic swelling that is partly in the mouth and partly in the neck
If we only address the intra-oral component of a plunging ranula through excision, it would just come back because the entire cyst has not been removed. Need to take a combined I/O and E/O approach to treatment therefore.
Describe the features of a lip mucocele
Mucous retention or mucous extravasation cyst (cannot tell until the cyst is removed)
Painless, soft fluid filled swelling on the lower lip
May appear bluish
More common in children
Often, patient will report a history of trauma
How do lip mucoceles arise?
Can be mucous retention cysts or mucous extravasation cysts
Can be caused by retention of mucous and saliva within the minor salivary glands or the escape of saliva from traumatised minor salivary glands in the FoM or the sublingual gland
Cannot tell what the pathophysiology of the cyst is until it is removed
List the methods that we can use to treat a lip mucocele
Excision (a cut made on top of the mucocele, removed using careful dissection). GOLD STANDARD approach, however comes with the risk of scarring, swelling, bleeding and bruising
Cryotherapy (involves liquid nitrogen or accelerated carbon dioxide to produce a very cold area on a probe. If we anaesthetise the area and place this cold probe on the tissues, we can freeze the tissues resulting in an ice ball. The ice ball expands and the ice crystals damage the cells and break down the cyst lining. And then the cyst resolves)
Why is there is a high risk of recurrence of lip mucoceles following removal?
Possible that the entire cyst lining has not been removed.
Or they may reoccur because the lower lip has 100s of minor salivary glands and as we’re working on removing one mucocele, the minor salivary gland next to it can become traumatised/obstructed leading to the formation of another cyst
A 12 year old patient presents with a soft fluid filled swelling on the lower lip. The swelling has a bluish tinge to it and the patient reports no pain. On inquiry, the patient states they dropped their phone on their lip not too long ago. What is the likely diagnosis and management for this patient?
Lower lip mucocele (mucous extravasation cyst as the patient reports a history of trauma to the associated region)
Excision (will require referral)
A patient presents with a slow growing, painless swelling on their upper lip. The patient reports no history of trauma in the region. What is the likely diagnosis and management protocol for this patient?
A salivary gland tumour
Referral via the 2 week wait referral pathway to rule out malignancy
A lower lip swelling is likely to be a ___________________ whereas an upper lip swelling is more likely to be a ___________________
Lip mucocele
Salivary gland tumour
Name 2 cysts that have a fibrous tissue lining instead of an epithelium lining
Solitary bone cysts
Aneurysmal bone cysts
