scr - os & histopathology - cysts

Question 1

what is a cyst

Answer 1

pathological cavity containing fluid / semi fluid / gaseous contents - NOT created by accumulation of pus

Question 2

WHO 2017 classification of cysts

Answer 2

epithelial / non epithelial
epithelial becomes odontogenic & non odontogenic
odontogenic becomes inflammatory & developmental

Question 3

epithelial odontogenic inflammatory cysts (4)

Answer 3

1. radicular cyst
2. residual cyst
3. paradental cyst
4. mandibular bifurcation cyst

Question 4

clinical criteria of radicular cyst

Answer 4

4th-5th decades
60% maxilla
lateral incisor region
NON VITAL TEETH
often asymptomatic
can produce alveolar bone expansion +/- discharge

Question 5

radiographic criteria of radicular cyst

Answer 5

round / ovoid radiolucency at root apex
unilocular / well defined
uniform radiolucency
corticated margin continuous with lamina dura key

Question 6

histopathologic criteria of radicular cyst

Answer 6

regular lining of non keratinised squamous epithelium that is often incomplete
deposits of cholesterol
vascular capsule
inflammatory infiltrate in capsule
CT capsule

Question 7

fibroblasts in radicular cyst

Answer 7

spindle shaped cells found with fibrous connective tissue

Question 8

neutrophils in radicular cyst

Answer 8

round cells with nuclei that are segmented into lobes of condensed chromatin connected by filaments

Question 9

plasma cells in radicular cyst

Answer 9

ovoid cells with eccentric nucleus with chromatin clumps arranged like a cartwheel

Question 10

cholesterol clefts

Answer 10

derived from breakdown of RBCs as a result of haemorrhage
may be few in no or form large mural nodules
usually associated with epithelial discontinuities & project into cyst lumen
cholesterol crystals found in cyst fluid
cholesterol dissolves out during prep of section leaving clefts (looks like wavy white lines on stain)

Question 11

hyaline / rushton bodies

Answer 11

translucent & pink staining lamellar bodies which are formed by cyst lining epithelium
eosinophilic bodies of varying size and shape of unknown origin that may represent some type of epithelial product
look like big pale splodges with dark outer staining

Question 12

cyst content from radicular cyst

Answer 12

watery straw coloured fluid

Question 13

aetiology of radicular cyst

Answer 13

inflammation from apical periodontitis following from pulp necrosis leading to proliferation of epithelium via rests of malassez (which are originally from hertwig’s epithelial root sheath in dental follicle) if these are not activated it will remain granuloma
cysts form by:
1. proliferating epithelium with central necrosis
OR
2. epithelium grows to surround an area of fluid

Question 14

to differentiate between granuloma & cyst

Answer 14

> 1cm diameter = cyst
<1cm diameter = granuloma
but can only diagnose following being sent to lab

Question 15

how does cyst expand

Answer 15

increase in osmotic pressure due to activation & proliferation of epithelial rests of malassez
& by cytokine mediated growth
often asymptomatic & slow growing with limited expansion

Question 16

tx options for radicular cysts

Answer 16

non surgical endo; RCT
surgical endo; periradicular surgery
apicectomy
XLA
last 3 are if it remains symptomatic

Question 17

paradental cyst

Answer 17

usually on lateral aspect of partially erupted vital teeth i.e. M3M where pericoronitis is inflammatory stimulus
related to neck or coronal 1/3 of tooth
tx =
SPM = enucleation
TPM = XLA

Question 18

mandibular buccal bifurcation cysts

Answer 18

in children
usually buccal aspect of erupting FPM

Question 19

developmental odontogenic cysts

Answer 19

1. dentigerous cyst
2. OKC
3. lateral periodontal cyst
4. gingival cysts
5. calcifying odontogenic cyst

Question 20

dentigerous cyst

Answer 20

associated with crown of u/e usually impacted tooth
commonly M3M
occurs when fluid accumulated between crown & reduced enamel epithelium (from enamel organ) dilating tooth follicle & preventing eruption
cyst attached to ACJ of u/e tooth

Question 21

clinical criteria of dentigerous cyst

Answer 21

M>F
2nd-3rd decade
asymptomatic
often incidental finding
tooth missing from arch

Question 22

radiographic criteria of dentigerous cyst

Answer 22

round / ovoid
well defined unilocular / uniform radiolucency
corticated margins
attached at ADJ of tooth
larger cysts may envelope root of tooth
expand symmetrically initially but larger may expand unilaterally

Question 23

histopathological criteria

Answer 23

thin non keratinised
stratified squamous epithelium
no significant inflammation

Question 24

why is dentigerous cyst commonly lower 8s and upper 3s

Answer 24

they have the highest rate of impaction

Question 25

follicular size v dentigerous cyst

Answer 25

<2.5mm = follicle
>4.2mm = probable cyst
>10mm = definite cyst
asymmetrical radiolucency = cyst

Question 26

tx of dentigerous cyst

Answer 26

1. XLA of u/e tooth
2. enucleation
3. marsupialisation

Question 27

variation of dentigerous cyst

Answer 27

eruption cyst
soft tissue variation
caused by lack of separation of follicle & enlargement around tooth
commonly primary incisors / FPMs in children

Question 28

OKC

Answer 28

3rd most common after radicular & dentigerous
originates from tooth structure but no specific relationship to teeth
arises from cell rests of serres which originates from remnants of dental lamina

Question 29

clinical criteria of OKC

Answer 29

M>F
wide age range
70-80% mandible
usually asymptomatic unless infected
if infected white line of corticated margin is lost

Question 30

radiographic criteria of OKC

Answer 30

oval
well defined
uniform radiolucency
uni or multilocular

Question 31

histopathological criteria of OKC

Answer 31

thin CT wall
uninflamed
thin parakeratinised stratified squamous epithelium
no RETE PEGS with epithelium & CT
pallisading of basal cell nuclei
presence of daughter / satellite cells due epithelium being able to separate from wall following surgery leads to high recurrence rate - look like big pink / purple dots

Question 32

to diagnose OKC

Answer 32

aspiration biopsy
thick grey / white cheesy material with keratinous debris
should contain squames & low soluble protein content (<4g/dl)
squame = superficial keratinised squamous cell generally anucleated & increased no indicates abnormal keratinisation

Question 33

tx of OKC

Answer 33

1. enucleation
2. marsupialisation

Question 34

if multiple OKCs

Answer 34

associated with basal cell naevus syndrome which inc:
- basal cell carcinoma
- skeletal abnormalities
- skin pigmentation
aka gorlin goltz syndrome

Question 35

lateral periodontal cyst

Answer 35

rare
associated with lateral surface of tooth root
commonly canine / premolar region
vital tooth
asymptomatic / incidental finding

Question 36

clinical criteria of lateral periodontal cyst

Answer 36

middle aged
may present with expansion
vital
mandible > maxilla

Question 37

radiographic criteria of lateral periodontal cyst

Answer 37

well demarcated radiolucency
attached to side of root

Question 38

histopathological criteria of lateral periodontal cyst

Answer 38

thin stratified squamous epithelium
similar to gingival cysts

Question 39

gingival cysts

Answer 39

derived from remnants of dental lamina i.e. rests of serres in gingival / alveolar soft tissues
in adults = <1cm pink / blue sessile swellings
in children = bohn’s nodules (similar to epstein pearls which are on palate but aren’t odontogenic) naturally degenerate

Question 40

calcifying odontogenic cyst clinical criteria

Answer 40

usually <40yrs
75% intraosseous
mainly anterior to FPM
small usually 1-3cm diameter
shape variable
monolocular
adjacent teeth usually displaced +/- resorbed
bony expansion

Question 41

calcifying odontogenic cyst radiographic criteria

Answer 41

initially radiolucent
uni or mulitlocular
in more advanced stage contains variable calcified radiopaque material
rarely recur - benign course

Question 42

non odontogenic epithelial cysts

Answer 42

nasopalatine duct cyst

Question 43

NPD cyst clinical criteria

Answer 43

M>F
5th-6th decades
often asymptomatic
may have salty taste & vital teeth i.e. no infection
slowly enlarging swelling anterior midline of palate
always involves midline
but not always symmetrical
larger cysts can displace teeth

Question 44

NPD cyst radiographic criteria

Answer 44

well defined & corticated margin
round / ovoid / heart shaped (due to superimposition of anterior nasal spine) radiolucency
over roots of central incisors
sclerotic margin

Question 45

NPD cyst histopathological criteria

Answer 45

non keratinised stratified squamous with modified respiratory epithelium

Question 46

cyst v incisive fossa

Answer 46

<6mm = incisive fossa
6-10mm = monitor
>10mm = suspect cyst

Question 47

non epithelial jaw cysts

Answer 47

solitary bone cyst - asymptomatic, incidental, aetiology unknown
aneurysmal bone cyst - blood aspirated into this during biopsy
stafne’s idiopathic bone cavity - not a cyst just a depression / concavity in bone, only occurs in mandible

Question 48

mx of cysts

Answer 48

referral
initial consultation
radiographs
biopsy
diagnosis
txp & consent

Question 49

what can you not enucleate

Answer 49

ameloblastoma

Question 50

cyst enucleation

Answer 50

removal of entire cyst lining & contents useful for radicular / residual / dentigerous / OKC

Question 51

complications of enucleation (4)

Answer 51

• damage to IAN
• communication with maxillary sinus
• pathological # of mandible
• risk of recurrence

Question 52

marsupialisation

Answer 52

creation of surgical window in wall of cyst to remove contents & suture surrounding epithelium
encourages cyst to decrease in size for later enucleation (can take 1yr)
tube / grommit insertion
useful for large cyst

Question 53

+/- of marsupialisation

Answer 53

+ simple
+ may spare vital structures
+ later enucleation
- opening may close
- long tx prior to completion
- complete lining unavailable for histopathology
- difficult to keep clean & a lot of aftercare required
- chance of reinfection
- uncomfortable

Question 54

segmental resection

Answer 54

removal of cyst with margin of normal bone
mainly for ameloblastoma / sarcoma
normally require 2ndary procedure for reconstruction of defect