Cysts of the Jaws II

Question 1

Classification of odontogenic cysts?

Answer 1

Developmental:

• Follicular cysts: dentigerous cysts, eruption cysts
• Odontogenic keratocysts
• Gingival cysts
• Lateral periodontal cyst
• Botryroid odontogenic cyst
• Glandular odontogenic cyst
• Calcifying odontogenic cyst
• Orthokeratinised odontogenic cyst

Question 2

What is a follicular cyst? Types?

Answer 2

A cyst which surrounds the crown of an unerupted tooth and arises from the reduced enamel (follicular) epithelium

• Dentigerous - associated with an impacted tooth
• Eruption - associated with an erupting tooth, more common in children

Question 3

Pathogenesis of follicular cysts?

Answer 3

Impacted tooth = follicular epithelium proliferates and fluid accumulation between crown and epithelium = epi will shed = cyst forms

Question 4

Radiographic features of follicular cysts?

Answer 4

Corticated outline
Impacted tooth often displaced by cyst
Cyst attaches to ACJ

Question 5

Follicular cyst histology?

Answer 5

2 layers thick and cuboidal cells = reduced enamel epithelium
Can be thicker but still thin - Non-keratinised SS epi
Wall of cyst is NOT filled with inflammatory cells

Question 6

What is an eruption cyst?

How to manage this?

Answer 6

If tooth is erupting but something stops it - swelling which gives it a blue tinge, lies just beneath the oral mucosa
- Incise it and tooth will erupt

Question 7

What is an odontogenic keratocyst?

Answer 7

A cyst arising in the tooth bearing area and characterised by a thin lining of parakeratinised epithelium
Arises from dental lamina or its remnants
May replace a tooth

Question 8

Pathogenesis of odontogenic keratocyst?

Answer 8

Remnants of dental lamina - epithelial proliferation (may be due to genetics or trauma) = cyst develops

Question 9

Odontogenic keratocyst features?

Answer 9

Lining: parakeratinised SSE
62% in males
75% in mandible
50% in lower 3rd molar area
50% associated with unerupted tooth

Often little or no bucco-lingual expansion
Classic area = angle of mandible

Question 10

Histology of Odontogenic keratocyst?

Answer 10

Lumen
Lining = thin paraketinised epithelium that is folded (pink stripe with nuclei in it) and basal cell layer are lined up like a picket fence. Basal cells may pull up from the basement membrane = reverse subnuclear polarity
Wall = fibrous CT, no/few inflam cells (may be inflamed if associated with a PE tooth)

Question 11

Odontogenic keratocyst recurrence?

Answer 11

% recurrence varies - around 20%
Reoccur due to:
- Fragility of the lining - when removing the cyst it is easy to leave some lining behind
- Finger like cyst extensions into cancellous bone
- Rapid proliferation of the epithelium
- Daughter cysts

Question 12

Odontogenic keratocyst - basal cell naevus syndrome/gorlin goltz syndrome features?

Answer 12

AD - PTCH mutation
Multiple and recurrent odontogenic keraocysts
Basal cell carcinomas of skin
Frontal bossing - large forehead
Skeletal abnormalities (bifid ribs)
Cranial abnormalities (calcification of falx cerebri)

Question 13

What can odontogenic keratocysts be?

Answer 13

Can be solid - lots of keratin in them = aggressive and destructive

Question 14

Odontogenic keratocyst - why may people think it should be classified as a benign neoplasm?

Answer 14

High rate of proliferation in the epithelium lining
High rate of recurrence
Aggressive and infiltrative growth
Association with basal cell carcinoma in BCNS/gorlin goltz syndrome
- Molecular changes similar to basal cell carcinoma
- PTCH mutation in BCC and Gorlin’s syndrome

Question 15

What is a lateral periodontal cyst?

Answer 15

Occurs on the lateral aspect or between the roots of vital teeth
Is is developmental in origin - rests of Serres
Occasionally it is multilocular and called botryoid odontogenic cyst

Question 16

Histology of lateral periodontal cyst?

Answer 16

May be multilocular

Localised thickening of lining is common

Question 17

Gingival cysts of infants?

Answer 17

Arise from dental lamina rests in the alveolar mucosa of infants
Lined by thin parakeratinised epithelium
White spots on ridge - will come and go

Question 18

Gingival cysts of adults?

Answer 18

Arise from dental lamina rests in the attached gingiva
Lined by thin non-keratinised epithelium
Need to be removed

Question 19

Gingival cyst histology?

Answer 19

Under epi, not within bone, lined by non-keratinised SSE

Question 20

What is a glandular odontogenic cyst?

Answer 20

A cyst characterised by cuboidal or columnar epithelium with mucous production
Forms duct like or glandular structures
Rare but large and destructive
Can recur

Question 21

Glandular odontogenic cyst histology?

Answer 21

Epithelial thickenings

Mucous cells and ducts

Question 22

Calcifying odontogenic cyst features?

Answer 22

Age 10-30, mandible or maxilla
Radiolucency, may have calcifications
Histology
- Cyst lined by ameloblastoma like epithelium with ghost cells and dentine in the wall
- May be solid - ‘odontogenic ghost cell tumour’

Question 23

Non-odontogenic cyst - types?

Answer 23

Nasopalatine duct cyst

Nasolabial cyst

Question 24

What is a nasopalatine duct cyst?

Answer 24

Arise in the nasopalatine (incisive) canal from epithelial residues of the nasopalatine duct
Lined by resp epithelium or SSE or both

Question 25

How do nasopalatine duct cysts form?

Answer 25

Hard palate forms by fusion of medial and lateral palatine processes = where they all join is the nasopalatine duct (where the incisive papilla is) = where cyst forms = epi left = radiolucency in centre of maxilla

Question 26

What is a nasolabial cyst?

Answer 26

Arises in the soft tissue overlying the alveolar process at the base of the nostril, deep to the nasolabial fold
It probably arises from remnants of the nasolacrimal duct and is usually lined by pseudostratified columnar epithelium

Question 27

Examples of cystic lesions in the jaws, without an epithelial lining?

Answer 27

Solitary (simple) bone cyst

Safne’s bone cavity - often at angle of mandible, below IAN nerve