Cysts of the Jaw & Oral Regions Flashcards
What is a cyst?
Pathological cavity containing fluid, semi-fluid or gas
Often lined by epithelium
What can the classification of a cyst be based on?
Location (jaw/soft tissues/maxillary antrum)
Cell type (epithelial/non-epithelial)
Pathogenesis (Developmental/inflammatory)
What are the 2 main categories of cysts based on WHO (1992)?
Epithelial
Non-epithelial
What are the 2 types of epithelial cysts?
Odontogenic & non-odontogenic
What are the 2 types of odontogenic systs?
Inflammatory odontogenic systs
Developmental odontogenic cysts
What are the 3 types of inflammatory odontogenic cysts?
Radicular cyst (apical & lateral)
Paradental cyst
Residual cyst
What are the 5 types of developmental odontogenic cysts?
Odontogenic keratocyst
Dentigerous cyst (Follicular/eruption cyst)
Lateral periodontal cyst
Glandular odontogenic cyst (sialo-odontogenic)
Gingival cyst of adults
Where are epithelial, non-odontogenic cysts found?
Fissures
Name 3 types of epithelial, non-odontogenic cysts
Median palatine cyst
Nasiolabial cyst
Nasopalatine cyst (incisive canal cyst)
Are non-epithelial cysts odontogenic or non-odontogenic?
Non-odontogenic
Name 2 types of non-epithelial cysts
Solitary bone cyst
Aneurysmal bone cyst
Where are the 3 sources from which the lining of epithelium is derived from?
Rests of Malassez
Reduced enamel epithelium
Remnants of the dental lamina
Which cysts have epithelium derived from the Rests of Malassez?
Radicular cyst
Residual cyst
Which cysts have epithelium derived from reduced enamel epithelium?
Dentigerous cyst
Eruption cyst
Which cysts have epithelium derived from remnants of the dental lamina?
Odontogenic keratocyst
Lateral periodontal cyst
Gingival cyst of adult
Glandular odontogenic cyst
What are the 3 things needed for a cyst to form? (Pathogenesis)
- Source of epithelium
- Stimulus for cavitation + epithelial cell proliferation
- Mechanism(s) for continued cyst growth + accompanying bone resorption (cyst will only grow if bone is resorbed)
What are the sources of epithelium of inflammatory cysts and how do they proliferate?
Epithelial cell rests of Malassez derived from remnants of Hertwig’s root sheath
Cell rests dotted throughout PDL, when trapped within periapical granuloma, with correct stimulus it proliferates
What is the source of epithelium of dentigerous cysts and how does it proliferate?
Reduced enamel epithelium (REE)
Space between REE + enamel leads to cyst formation
What is the source of epithelium of an odontogenic keratocyst>
Remnants of dental lamina (initial buds before tooth germ, aka Glands of Serres)
What is the source of epithelium of a nasopalatine duct cyst?
Nasopalatine duct epithelium - between 2 palatine processes
What is the source of epithelium of a nasolabial cyst?
Epithelial remnants at site of fissures (between processes)
What is the source of epithelium of a mucous retention cyst?
Salivary duct epithelium
What is the source of epithelium of a lympoepithelial/branchial cyst?
Inclusions of epithelium in lymphoid tissue
What is the source of epithelium of a thyroglossal cyst?
Thyroglossal duct epithelium
What are the stimuli for epithelial proliferation + cavitation?
Inflammation/inflammatory stimulus
Inflammatory cells secrete cytokines
Possible links to genetic defects in a tumour suppressor gene in a subset of odontogenic keratocysts
Genetic stimulus
Give examples where inflammation/inflammatory would be a stimulus for epithelial proliferation + cavitation
Site-specific: e.g. necrotic pulp -> PA granuloma -> inflammatory cyst
Periodontal pocket - lateral periodontal inflammatory dental cyst (if lots of inflammation)
Which cytokines would be released by inflammatory cells for epithelial proliferation + cavitation?
IL-1, IL-6 + TNF + growth factors
Epidermal growth factor (EGF) + transforming growth factor (TGF) beta
What are the 3 mechanisms of cyst growth?
- Internal hydraulic pressure
- Bone resorption
- Epithelial growth
Describe the internal hydraulic pressure mechanism of cystic growth and which cysts it occurs in
Expansion of inflammatory + dentigerous cysts
Protein accumulation within cyst walls as semipermeable membrane due to osmotic pressure
Fluid accumulates within cyst lumen creating positive pressure in the cysts -> encouraging bone resorption
Describe the bone resorption method of cystic growth
Pro-inflammatory cytokines IL-1 (released by macrophages), TNF + PGER (released by fibroblasts) induce bone resorption
Produced by inflammatory cells in cysts, stimulating bone resorption
Describe the epithelial growth method of cystic growth and where do we see it in particular
Growth factors such as EGF + TGF beta may cause pronounced proliferation of cyst epithelium
Particularly important in odontogenic keratocysts which show pronounced mural growth even in absence of marked inflammation
What are the general clinical features of cysts?
Swelling
Displacement/loosening of teeth
Pain (if infected)
Eggshell cracking
Sign of fluctuance - movable/compressible; the larger the cycts, the more fluctuance
What type of radiograph would you take for small cystic lesions?
I/O PA
How many rads are usually taken for cysts? How are they taken and why?
2 images taken at right angles to each other
So can locate where the cyst is
Which radiographs are taken of the maxilla?
PA + oblique occlusal
OPG + lateral oblique
Occipitomental (OM)
True lateral
CBCT
Which radiographs are taken of the mandible?
PA + true occlusal
OPG + lateral oblique
PA (Ap) of mandible
CBCT
What are the radiological signs to look for?
Location
Size
Shape
Margin
Effect on adjacent structures
How do cysts appear clinically?
Well-defined, round or oval radiolucency
Well-defined margin
What type of teeth are radicular cysts related to?
Related to non-vital tooth
Where do radicular cysts develop within?
Periapical granuloma
Describe how a radicular cyst would look on a radiograph
Unilocular, well defined, well corticated radiolucency at apex of non-vital tooth
Where is the commonest site of radicular cysts?
Upper incisors
What are the peak ages for a radicular cyst?
4-5th decade
Describe the nature of radicular cysts’ growth
Regular growth limited buccal expansion
Usually continuous with the lamina dura of root of affected tooth
Do radicular cysts cause resorption?
Do not usually cause resorption
If long-standing can cause resorption + displacement of adjacent teeth
How are radicular cysts treated?
Endo
surgical extraction
What can form if a radicular cyst is retained following an extraction?
Residual radicular cyst
Describe what a residual radicular cyst looks like on a radiograph
Well-defined, round/oval radiolucency
Where are residual radicular cysts always found?
Edentulous area
After extraction of affected tooth
What is the key histology of a radicular cyst?
Thick wall of fibrous granulation tissue
Inflamed - chronic + acute inflammatory cells (neutrophils)
Cholestrol clefts + foreign body giant cells in wall/lumen
Mucous cells particularly in maxillary cysts, due to location - hyaline bodies may be seen
Describe the epithelial lining of a radicular cyst
Non-keratinised stratified squamous
Variable thickness most common but can be thin/attenuated in long-standing cysts
What is inside the lumen of a radicular cyst?
Pale pink serous exudate, macrophages, desquamated epithelial cells, inflammatory cells + cholestrol clefts
What are dentigerous cysts also known as?
Eruption cysts
What are dentigerous cysts attached to?
Attached at CEJ surrounding crown of unerupted 8s + 3s (typically enveloping crown)
What is the peak age for a dentigerous cyst?
3-4th decade
When is a cyst expected in regard to the follicular space?
If it exceeds 3mm
Describe the radiological appearance of a dentigerous cyst
Unilocular, well-corticated radiolucency, late buccal expansion
Classically crown of associated tooth lies centrally within cyst
What is the treatment of a dentigerous cyst?
Surgical removal/uncover tooth
Do dentigerous cysts recur?
No recurrence
Describe the key histology of dentigerous cysts
Cyst wall variably thick often with a bluish myxoid appearance like dental follicle
Pink exudate sometimes in cavity
Mucous metaplasia common
Describe the epithelial lining of dentigerous cysts
Non-keratinised stratified squamous epithelium on a flat basement membrane 2-5 cells thick
If inflamed lining looks like inflammatory cysts
What is found in the lumen of dentigerous cysts?
Pink serous exudate, cholestrol clefts
What is the commonest site of a odontogenic keratocyst?
Angle of mandible + ramus
Locularity of an odontogenic keratocyst?
Usually multilocular, but can be unilocular + associated with an unerupted tooth, very little expansion
What is the peak age of odontogenic keratocysts?
2nd + 3rd decades
How does an odontogenic keratocyst grow?
Through medullary bone with late buccal expansion
May be associated with tooth root resorption
What is the treatment for odontogenic keratocysts?
Surgical removal
Does recurrence occur with odontogenic keratocysts + why?
Recurrence is common
Due to difficulty in removal + daughter cysts
Multiple odontogenic keratocysts are associated with which syndrome?
Gorlin Goltz
What is another name for Gorlin Goltz syndrome?
Nevoid basal cell Carcinoma
What type of disease is Gorlin Goltz syndrome?
Rare autosomal disorder characterised by multiple basal cell carcinoma
List the clinical features of Gorlin Goltz syndrome
Developmental defects such as bifid ribs, spine + rib abnormalities
Palmar + plantar epidermal pits
Calcification of the falx cerebri
Relative macrocephaly, facial milia, frontal bossing
Key histology of odontogenic keratocysts in someone with Gorlin Goltz syndrome
Thin fibrous cyst wall
Normally uninflamed
Small daughter cysts may be in the wall
Epithelial lining is keratinised - normally parakeratinised with a corrugated surface - flat basement membrane
Basal cells darkly stained with reversal of nuclear polarity - like ameloblasts
Lumen filled with keratin
What is a lateral periodontal cyst?
Any cyst in the lateral periodontal region that is not an inflammatory cyst or an atypical odontogenic keratocyst
What are lateral periodontal cysts associated with?
Lateral roots of vital teeth
Describe the radiographic appearance of a lateral periodontal cyst
Usually very small, <1cm in diameter
Round, well-defined, corticated + normally unilocular
Can cause buccal expansion if very large
What is the key histology of a lateral periodontal cyst?
It is a developmental cyst so largely flat basement membrane
Epithelial layer is 2-5 cells thick
Thickened in areas to form swirled plaques
Scattered glycogen rich clear cells
May be multicystic
Fibrous cyst wall is thin + uniformed
Where are nasopalatine cysts found?
Midline, anterior maxilla, just posterior to upper central incisors
Associated with a vital maxillary incisor
At what age do nasopalatine cysts commonly form?
5-6th decade
Describe the radiological appearance of nasopalatine cysts
Well-defined, well-corticated monolocular radiolucency
Round/oval
How big are nasopalatine cysts?
> 6mm
What is the most common non-odontogenic cyst?
Nasopalatine cyst
Describe the key histology of nasopalatine cysts
Lining may be nonkeratinising stratified squamous or ciliated respiratory type epithelium, usually both
Look for big nerves + blood vessels in wall
When are solitary bone cysts likely to form?
Children + adolescents under 20 years
Where are solitary bone cysts found?
Body of mandible
Describe the radiographic appearance of a solitary bone cyst
Well corticated, monolocular radiolucency
Irregular outline
Describe the cavity of a solitary bone cyst
No wall/thin fibrous wall no epithelial lining
Cyst lumen often empty
Describe the key histology of a solitary bone cyst
Fibrovascular tissue only
No epithelial cyst lining
Occasional giant cells + haemosidenin pigment may be seen
What is an aneurysmal bone cyst often classified as?
Giant cell lesion
At what age are aneurysmal bone cysts found?
Children + young adults
Describe the radiographic appearance of an aneurysmal bone cyst
Multilocular radiolucency in the mandible with cortical expansion
Describe what the aneurysmal cyst is like
Partially cystic partially solid
Contains blood filled cystic spaces
Describe the key histology of the aneurysmal bone cyst
Localised proliferative lesion of vascular tissue, containing giant cells + granulation tissue therefore it is a soft tissue lesion
What are the 4 types of cysts in the soft tissues of the mouth, face + neck
Cysts of the salivary glands
Lymphoepithelial (Branchial cleft) cyst
Thyroglossal duct cysts
Dermoid + Epidermoid cysts
Name 3 types of cysts of the salivary glands
Mucous extravasation cyst
Mucous retention cyst
Ranula
Where is the most common site of a mucous extravasation cyst?
Lower lip is quite common
Causes of mucous extravasation cysts
Related to trauma - e.g. pt biting on lip
What is the key histology of a mucous extravasation cyst?
Surrounded by granulation tissue
When are mucous retention cysts likely to happen?
In older age
Why do mucous retention cysts occur?
Dilated salivary duct filled mucin
Related to ductal obstruction
When do lymphoepithelial (branchial) cleft cysts appear?
Late in childhood or in early adulthood
Describe the clinical appearance and location of a lympoepithelial (branchial cleft) cyst?
Presents as unilateral
Soft tissue fluctuant swelling
Typically appears in lateral aspect of neck, anterior to sternocleidomastoid muscle
What is the key histology of soft tissue cysts?
Look for an epithelial lining
Look for mucin
Look for a lymphoid stroma
From epithelial remnants within lymphoid tissue
Attenuated (reduced) epithelium surrounded by reactive lymphoid stroma
What are dermoid cysts?
Developmental anomalies occasionally in soft tissues of head + neck
Where are dermoid cysts found?
Entrapped epithelium normally in midline, floor of mouth above mylohyoid
What is the key histology of dermoid cysts?
Cyst lined by epidermis + skin
At what age are dermoid cysts found?
May be found at birth/in older patients
Majority are 15 + 35 y/o
F=M
How do thyroglossal cysts occur?
Developmental remnants of thyroglossal tract during descent of thyroid
Where do thyroglossal cysts occur?
In midline
What is the key histology of a thyroglossal cyst?
Cyst lined by attenuated/respiratory epithelium
Often some thyroid follicles in the cyst wall
What are cholesterol clefts?
Spaces left by cholesterol crystals during tissue processing
Cholesterol is derived from the breakdown of RBCs
Clefts are a feature of inflamed cysts + are non-specific
Where do we see mucous metaplasia?
Can be seen in any cysts but common in dentigerous cysts + maxillary cysts
Where are hyaline bodies found + what are they?
Found in odontogenic cysts
Only material secreted by odontogenic epithelium + similar to dental cuticle
Where do we see a flat basement membrane?
Normally associated with developmental odontogenic cysts -e.g. dentigerous + keratocysts
What are the 3 ways to investigate a cyst?
- Clinically
- Biopsy
- Radiologically
What is assessed clinically when investigating a cyst?
Site + vital/non-vital
Absent/unerupted tooth
Swelling
Eggshell cracking, fluctuation
Displacement/loosening of teeth
What are the 3 types of biopsies?
Aspiration
Excisional biopsy
Incisional biopsy
When would you carry out aspiration?
Aneurysmal bone cyst - looking for a blood-hemangioma
Pus
Serous exudate
Keratin either by smear onto cytology slide or estimation of soluble protein
When would you carry out an incisional biopsy?
When lesion extensive/reason to believe it is not a simple cyst
e.g. dif radiolucencies at angle of mandible
When would you carry out an excisional biopsy?
When lesion is small + amenable for excision
