Cysts

Question 1

What is a cyst?

Answer 1

A pathologial cavity having fluid , semi-fluid or gaseous contents and which is not created by the accumulation of pus

Question 2

Signs and symptoms of cysts?

Answer 2

• mostly benign unless infected

Question 3

What investigations to carry out for cysts?

Answer 3

initial
- periapical radiograph
- occlusal radiograaph
- Panoramic radiograph
supplemental
- cone beam CT (CBCT)
- Facial radiographs
- PA mandible

Question 4

How are cysts classified?

Answer 4

Structure - epithelium lined : non epithelial lining
Origin : odontogenic : non-odontogenic
Pathogenesis : developmental vs inflammatory

Question 5

Types of odontogenic developmental cysts?

Answer 5

• dentigerous cysts
• odontogenic keratocyst
• lateral periodontal cyst

Question 6

Types of odontogenic inflammatory cysts

Answer 6

• radicular cyst and residual cyst
• inflammatory collateral cyst (paradental and buccal bifurcation cyst)

Question 7

non odontogenic developmental cysts?

Answer 7

• nasopalatine duct cyst

Question 8

non epithelial cysts

Answer 8

• solitary bone cyst
• aneurysmal bone cyst

Question 9

What are odontogenic cysts?

Answer 9

They occur in tooth bearing areas
- most common cause of bony swelling in the jaws
- they are all lined with epithelium

Question 10

Odontogenic sources of epithelium?

Answer 10

• Rests of malassez - remnants of hertwig’s epithelial root sheath
• Rests of serres - remants of the dental lamina
• Reduced enamel epithelium - remnants of the enamel organ

Question 11

What are the most common odontogenic cysts?

Answer 11

• Radicular cysts (residual cyst) - 60%
• Dentigerous cysts (eruption cyst) - 18%
• Odontogenic keratocyst - 12%

Question 12

What is a radicular cyst?

Answer 12

• it is an inflammatory odontogenic cyst
• associated with non vital tooth
• initiated by chronic inflammation at apex of tooth due to pulp necrosis
• mostly affecting maxilla

Question 13

What is the presentation of a radicular cyst?

Answer 13

• asymptomatic unless indected
• slow growing with limited expansion
• radiolucency more than 15mm

Question 14

What are the radiographic features of radicular cysts?

Answer 14

• well defined, round or oval radiolucency
• corticated margin continuous with lamina dura of non vital tooth

Question 15

What might be the dental effects of radicular cysts?

Answer 15

• may cause displacement of adjacent structures
• may cause external root resorption

Question 16

What is the histology of radicular cysts

Answer 16

• epithelial lining (often incomplete)
• connective tissue capsule
• inflammation in capsule
• originate from epithelial cells of malaasez

Question 17

How due radicular cysts form?

Answer 17

• rests of malassez proliferate in periapical granuloma
• they can then form by proliferating epithelium with central necrosis or epithelium surrounds fluid area

Question 18

What are the two growth mechanisms for radicular cysts ?

Answer 18

• Osmotic effect with semi-permeable wall
• Cytokine mediated growth

Question 19

What are the histological features of radicular cysts?

Answer 19

• variable inflammation
• cholestrol clefts
• mucous metaplsia
• Hyaline/rushton bodies

Question 20

How can you describe radicular cysts on palpation?

Answer 20

eggshell crackling

Question 21

What are the two variants of radicular cysts?

Answer 21

• residual cyst : radicular cyst that persists after loss of tooth
• Lateral radicular cyst : associated with an accessory canal , located at side of tooth instead of apex

Question 22

What is an inflammatory collateral cyst?

Answer 22

it is an inflammatory odontogenic cyst associated with a vital tooth

Question 23

What are the types of inflammatory collateral cysts?

Answer 23

• paradental - distal aspect of partially erupted third molar
• Buccal bifurcation cyst - buccal aspect of mandibular first molar

Question 24

What is dentigerous cyst

Answer 24

It is a developmental odontogenic cyst associated with a crown of unerupted ot impacted tooth (mandibular 8s or upper 3s)
- associated with cystic change of dental follicle

Question 25

How are dentigerous cysts present radiographically?

Answer 25

- corticated margins attached to cemento-enamel junction of tooth - may displace involved tooth

Question 26

what is the histopathology of dentigerous cysts?

Answer 26

thin non keratinised stratified sqaumous epithelium

Question 27

How to differentiate between dentigerous cyst and enlarged follicle?

Answer 27

- if follicular space is 5mm or more - normal follicular space is 2-3mm - if radiolucency is asymmetrical consider cyst

Question 28

What is eruption cyst

Answer 28

- it is a variant of dentigerous cyst - contained within soft tissue rather than bone - associated with an erupting tooth (more commonly incisors and in children)

Question 29

What is odontogenic keratocyst?

Answer 29

It is a developmental odontogenic cyst that is not associated with teeth

Question 30

How does it grow?

Answer 30

- can enlarge in medullary bone - can have significant mesio-distal expansion without bucco-lingual expansion

Question 31

Histology of odonotogenic keratocyst

Answer 31

- Have cyst aspirate (low soluble protein content) - Have parakeratosis - basal palisading - loss of keratin if inflammed

Question 32

What is basal cell naevus syndrome?

Answer 32

- presents as multiple odontogenic keratocysts - can have calcification - known as gorlin-goltz syndrome - associated with multiple basal cell carcinomas

Question 33

Examples of non odontogenic cysts ?

Answer 33

nasopalatine duct cyst solitary bone cyst aneurysmal bone cyst

Question 34

What is nasopalatine duct cyst

Answer 34

- it arises from nasopalatine duct epithelial remnants and occurs in anterior maxilla - AKA incisive canal cyst

Question 35

What is the presentation of nasopalatine duct cyst?

Answer 35

- it is often asymptomatic - have salty discharge - large cysts may displace teeth or cause swelling in palate - always involve midline bit not always symmetrical

Question 36

What is the histology of nasopalatine cyst?

Answer 36

- variable epithelial lining - non keratinised startified squamous and modified respiratory

Question 37

What further investigations for histology?

Answer 37

- Aspirational biopsy - drainage of contents - Incisional biopsy - Partial removal - Excisional biopsy - complete removal

Question 38

What kind of fluid you might find when performing aspirational biopsy?

Answer 38

**inflammatory or developmental** clear straw coloured fluid **keratocyst** white or cream semi-solid fluid indicated keratocyst

Question 39

What is the purpose of incisional biopsy?

Answer 39

to obtain a sample of the lining for histological analysis

Question 40

how to perform incisional biopsy?

Answer 40

Usually under LA - select place where lesion appears superficial - raise mucoperiosteal flap - remove bone as required - incise and remove a section of the lining (this may be combined with marsupialisation)

Question 41

What are the treatment options of cysts?

Answer 41

Enucleation Marsupialisation

Question 42

What is enucleation?

Answer 42

all of the cystic lesion is removed

Question 43

What is marsupialisation?

Answer 43

- creation of a surgical window in the wall of the cyst, removing the content of the cysts and suturing the cyst wall to the surrounding epithelium - encourages the cyst to decrease in size and may be followed by enucleation at a later date

Question 44

What are the advantages of enucleation?

Answer 44

- whole lining can be examined pathologically - primary closure - little aftercare needed

Question 45

What are the contraindicatoins and disadvantages of enucleation?

Answer 45

- risk of mandibular fracture - may wish to preserve tooth for dentigerous cysts - old in age - incomplete removal of lining may lead to recurrance - damage to adjacent structures - Clott filled cavity may become infected

Question 46

What are the indications of marsupialisation?

Answer 46

- if enucleation would damage adjacent structures - difficult access to the area - may allow eruption of teeth affected by a dentigerous cyst - Elderly or medically compromised patients that cannot withstand complex surgery - very large cysts which would risk jaw fracture if enucleation was performed - can combine with enucleation as a later procedure

Question 47

What are the advantages of marsupialisation?

Answer 47

- simple to perform - may spare vital structures

Question 48

What are the contraindications of marsupialisation?

Answer 48

- opening may close and cyst ay reform - complete lining not available for histology - difficult to keep clean and lots of aftercare needed - long time to fill in