Odontogenic cysts

Question 1

What is a cyst?

Answer 1

A cyst is a pathological cavity with fluid, semi-fluid or gaseous contents and is not created by an accumulation of pus.

Question 2

What are the different types of jaw cysts?

Answer 2

1. EPITHELIAL CYSTS:

 Odontogenic cysts - inflammatory - developmental

 Non odontogenic cysts (nasopalatine duct cyst, nasolabial cyst)

2. NON-EPITHELIALISED PRIMARY BONE CYSTS
   - Solitary bone cyst (simple, haemorrhagic)
   - Aneurysmal bone cyst
3. INFLAMMATORY ODONTOGENIC CYSTS - Radicular - Paradental
4. DEVELOPMENTAL ODONTOGENIC CYSTS:

 Dentigerous (follicular cyst)

 Eruption cyst

 Gingival cysts - infants

 Gingival cysts– adults

 Keratocyst

 Others- Lateral periodontal cysts, Sialo-odontogenic cysts

Question 3

What is the relative frequency of odontogenic cysts?

Answer 3

Radicular = 60-70% Dentigerous = 10-15% Keratocyst = 5-10& Nasopalatine = 5-10% Lateral periodontal = <1%

Question 4

What’s a radicular cyst?

Answer 4

 Commonest odontogenic cyst (60-70%)  Arises from the epithelial cell rests of Malassez in the periodontal ligament, usually after death of the pulp

Question 5

What are the clinical features of a radicular cyst?

Answer 5

 60 - 75% of jaw cysts  Peak in 4th and 5th decades  Rare in deciduous teeth  Common in maxillary incisors due to: - palatal invaginations - small teeth - trauma  Symptomless or expansion ‘egg-shell crackling’  Fluctuation  Infection leads to pain  Non-vital tooth  Tooth mobility or displacement

Question 6

What are the radiographical features of a radicular cyst?

Answer 6

 Rounded clearly defined radiolucency  Apex of tooth  Condensed radiopaque periphery - may be continuous with lamina dura  Lateral locations  Residual cysts

Question 7

What is a dentigerous cyst?

Answer 7

Cyst enclosing the crown of an unerupted tooth

Attached to cemento - enamel junction

Follicular cyst

Question 8

What are the clinical features of a dentigerous cyst?

Answer 8

10-15% of jaw cysts

Children and young adults

Permanent teeth

M:F 1.6:1

Painless enlargement - missing tooth

Pain and swelling if infected

Tilting of teeth

Root resorption

Question 9

What are the radiological feautres of a dentigerous cyst?

Answer 9

Crown of unerupted tooth

Permanent teeth

Round, unilocular

Well defined, corticated

Uniformly radiolucent

Question 10

What’s the pathology of a dentigerous cyst?

Answer 10

 Clear yellow fluid - cholesterol

 Purulent if infected

 Lined by flattened, attenuated non-keratinised stratified squamous epithelium

 Continuous with reduced enamel epithelium

 Mucous and ciliated columnar metaplasia

 Fibrous wall + variable inflammation

Question 11

What’s the pathogenesis of a dentigerous cyst?

Question 12

What’s an eruption cyst?

Answer 12

Extra-alveolar follicular cyst

Deciduous tooth or permanent molar

Fluctuant bluish swelling

Haemorrhage into cyst is common

Most spontaneously resolve

 Marsupialise

Question 13

What’s a gingival cyst?

Answer 13

Bohn’s nodules, Epstein’s pearls

Common in newborn and up to 3 months

Usually rupture or spontaneously involute

2 - 3 mm keratinising stratified squamous epithelium

Arise from Serres rests

Question 14

Histology of a ginigval cyst:

Answer 14

Question 15

What’s a ginigval cyst in an adult like?

Answer 15

 Slow-growing, usually less than 1cm in diameter

 Free or attached gingiva or interdental papilla

 Tooth vital

 Pathogenesis:

? odontogenic rests ? implantation

Question 16

What’s an odontogenic keratocyst?

Answer 16

A rare and benign but locally aggressive deveoplmetal cystic neoplasm. Most often affects the posterior mandible.

They’re thought to arise from the dental lamina and associated with impacted teeth. Affects males same as females.

CLINICAL:

Often asymptomatic and only found radiographically but may present with pain, swelling, discharge, pathological fracture, tooth displacement, buccal expansion

10% multiple

High recurrence rate

Question 17

What are the radiological features of an odontogenic keratocyst?

Answer 17

Well demarcated radiolucent area

Unilocular, often with a scalloped periphery

 Multilocular

? dentigerous (envelopmental)

Root or tooth displacement

Question 18

What’s the histopathology of a keratocyst?

Answer 18

 Regular stratified squamous epithelium

 5 - 8 cells thick

 Palisaded basal layer

 Corrugated surface, usually parakeratinised

 Thin, friable fibrous capsule

 Satellite (daughter) cysts

Question 19

What’s the recurrence likelyhood of an odontogenic keratocyst?

Answer 19

6 - 60%

Size and infiltrative nature

Tendency to multiplicity and satellite cysts

Intrinsic growth potential ‘hollow benign neoplasm’

Thin, friable capsule

Genetic - multiple basal cell naevus syndrome (Gorlin and Goltz)

? malignant potential

Question 20

What’s Gorlin-Goltz Syndrome?

Answer 20

Skeletal abnormalities - bifid ribs

• spine defects

Frontal bossing and hypertelorism

Multiple keratocysts

Multiple basal cell naevi and carcinomas

Calcification of the falx cerebri

PATCHED (PTCH) gene (9q22)- receptor

Question 21

What’s the pathogenesis of Gorlin-Goltz Syndrome? and how deos enlargement occur?

Answer 21

Pathogenesis = Derived from dental lamina or its remnants - rests or glands of Serres

Enlargement =

 Varies from cancellous without expansion to large, especially in angle and ramus of mandible

 Mural growth

Question 22

What’s an orthokeratinised keratocyst

Answer 22

 12% of keratocysts

 Basal layer cuboidal or flattened

 Orthokeratinised surface

 Granular cell layer

 Behaviour

• 4% recurrence rate

Question 23

What are the clinical features of a lateral periodontal cyst?

Answer 23

Lateral surface of roots

Lower canine/premolar area

Upper lateral incisors

Rare below 20 years

Usually asymptomatic

Occasionally swelling +/- pain

Adjacent teeth vital

Question 24

What are the radiological feautures of a lateral periodontal cyst?

Answer 24

 Well defined, uniform radiolucent area lateral to tooth

 Usually < 1cm

 Round, oval, unilocular

 Well defined and corticated

 Teeth may be displaced

Question 25

What’s the pathology of a lateral periodontal cyst?

Answer 25

 Thin non-keratinised stratified squamous epithelium

 Nodular epithelial thickenings or plaques

 ? derived from cell rests of Malassez

 Multilocular variants - botryoid odontogenic cyst

Question 26

What are the clinical and radiological features of a sialo-odontogenic cyst (glandular odontogenic cyst)?

Answer 26

CLINICAL FEATURES:

 Rare  Middle aged or older  Anterior mandible  Can be large and destructive  Pain and swelling  Can recur

RADIOGRAPHY:

 Unilocular or multilocular radiolucency  Well defined borders

Question 27

What’s the pathology of a sialo-odontogenic cyst?

Answer 27

Epithelium of varying thickness

Irregular or papillary surface with surface cuboidal or ciliated cells

Mucous cells

Epithelial whorls or plaques

Question 28

What’s the embryological derivation of odontogenic cysts?

Answer 28

See image

Question 30

What’s a nasopalatine duct cyst?

Answer 30

 Incisive canal cyst

 Remnants of nasopalatine duct

 M:F 4:1

 30 - 60 years

 Swelling of midline of palate labial

 Pain and discharge - mucoid and salty - purulent and foul

 Vitality of anterior teeth

Question 31

What’s the radiology of a nasopalatine duct cyst?

Answer 31

 Well defined radiolucency between roots of central incisors

 Roots may diverge

 Intact lamina dura

Question 32

What’s the histopathology of a nasopalatine duct cyst?

Answer 32

 Respiratory type epithelium

 Stratified squamous epithelium

 Blood vessels and nerves in wall

Question 33

What are the clinical feautres of a nasolabial duct cyst?

Answer 33

Swelling in nasolabial fold below alae and leading to loss of fold

Sometimes bilateral

Swelling, pain, difficulty in nasal breathing or wearing denture

Question 34

What’s the pathogenesis and histopahtology of a nasolabial cyst?

Answer 34

PATHOGENESIS:

 ? epithelium enclosed at a site of ‘fusion’ of globular, lateral nasal and maxillary processes - unlikely

 ? remnants of embryonic nasolacrimal duct HISTOPATHOLOGY:

 Non-ciliated columnar, respiratory type or stratified squamous epithelium

Question 35

What’s an aneurysmal bone cyst?

Answer 35

A type of non-epithelialised primary bone cyst:

most common in

Radiolucent area bulging into adjacent soft tissue

Blood filled spaces

Giant cells, haemorrhage, osteoid

? associated fibro-osseous lesion

Question 36

What’s a simple bone cyst?

Answer 36

A type of non-epithelialised primary bone cyst:

 Solitary, haemorrhagic, traumatic

 Rare

 Mandible, usually in second decade

 Radiolucent area extending between roots, usually without expansion

 Resolves with minimal intervention