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ODONTOGENIC
CYSTS AND
TUMOURS
Odontogenesis, Odontogenic Cysts, & Odontogenic Tumors
I. Odontogenesis
-The first signs of tooth development take place around
1. embryonic day 37 (6th week of fetal life)
2. with the budding of the epithelium
3. from the crest of the future alveolar ridge.
-Development of the entire primary dentition (20 teeth) is
initiated
b/w the 6th & 8th week of embryonic development.
-Succedaneous teeth (20 teeth) begin development
b/w the 20th week in utero &
the 10th month after birth;
the permanent molars (12 teeth) follow.
Dental lamina
Stages of tooth development
1. Bud stage
2. Cap stage
3. Bell stage
Root Formation
1
DENTAL LAMINA
1. Epithelial band of cells
2. formed by proliferation of overlying ectoderm into
ectomesenchyme;
3. Serves as primordium for the ectodermal portion of the teeth
(enamel).
BUD STAGE
1. Down growths from the dental lamina
2. into the ectomesenchyme
3. representing the beginning of the enamel organ
4. which gives rise to the tooth enamel.
CAP STAGE
1. Invagination in the deep surface of the enamel organ gives it a
cap shape.
2. Underlying ectomesenchyme within invagination is the dental
papilla, which gives rise to the pulp and dentin.
3. Ectomesenchyme surrounding the enamel organ and dental
papilla is the dental sac which gives rise to the cementum and
periodontal ligament.
BELL STAGE
1. The invagination in the enamel organ deepens giving it a bell
shape.
2. At this stage, four different cell types can be seen within the
enamel organ:
3. Inner Enamel Epithelium
4. Stratum Intermedium
5. Stellate Reticulum
6. Outer Enamel Epithelium
ADVANCED BELL STAGE
1. Inner enamel epithelium differentiates into ameloblasts
2. which form enamel,
3. which induces differentiation of the adjacent cell layer of the
dental papilla
4. Into odontoblasts which form dentin.
2
ROOT FORMATION
1. This is influenced by the epithelial root sheath of Hertwig
2. which consists of the outer and inner enamel epithelium
3. fused together in the area of the future cementoenamel
junction.
4. The inner enamel epithelium induces differentiation of the outer
layer of the dental papilla into odontoblasts which form dentin.
ROOT FORMATION
1. The formation of dentin causes Hertwig’s sheath to break down
bringing the dental sac into contact with the dentin, inducing
differentiation into cementoblasts which form cementum.
2. Remnants of Hertwig’s sheath are called rests of Malassez.
3. Remnants of the dental lamina are called rests of Serres.
ODONTOGENIC CYSTS AND TUMOURS
ODONTOGENIC CYSTS
1. Pathological spaces lined by epithelium of odontogenic origin.
2. Dentigerous Cyst (Follicular Cyst)
3. Eruption Cyst (Eruption Hematoma)
4. Primordial Cyst
5. Odontogenic Keratocyst
ODONTOGENIC CYSTS
1. Gingival Cyst of the Newborn
2. Gingival Cyst of the Adult
3. Lateral Periodontal Cyst
4. Calcifying Odontogenic Cyst (Gorlin Cyst)
5. Glandular Odontogenic Cyst
6. Inflammatory Cyst
DENTIGEROUS CYST (Follicular Cyst)
1. Originates by separation of follicle from crown of tooth,
2. encloses the crown of an unerupted tooth and
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3. attaches at the cemento-enamel junction.
CLINICAL FEATURES
1. Most commonly associated with unerupted mandibular third
molars.
2. Any age, most frequent between 10 - 30 years of age
3. Slight Male predilection.
DENTIGEROUS CYST (Follicular Cyst)
HISTOPATHOLOGY
1. Fibrous wall which may show inflammation,
2. may have small islands of odontogenic epithelial rests,
3. lining consists of reduced enamel epithelium
4. which may occasionally show squamous metaplasia,
5. mucous cells and areas of keratinization may also be seen.
TREATMENT AND PROGNOSIS
1. Enucleation with tooth removal.
2. Prognosis excellent with rare recurrence after complete
removal.
ERUPTION CYST (Eruption Hematoma)
Soft tissue analogue of the Dentigerous Cyst
CLINICAL FEATURES
1. Soft translucent swelling overlying crown of unerupted tooth.
2. Usually seen in children under 10 years of age.
3. Most common in the mandibular molar region.
4. Trauma may result in blood in cystic fluid giving it a darker color
(eruption hematoma).
ERUPTION CYST (Eruption Hematoma)TREATMENT AND
PROGNOSIS
1. Usually ruptures spontaneously,
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2. the roof of the cyst may also be excised.
PRIMORDIAL CYST
1. This term was used for cysts that arose in place of missing
teeth.
2. On histopathologic examination, these cysts were found to be
odontogenic keratocysts,
3. therefore, the term primordial cyst is no longer used.
ODONTOGENIC KERATOCYST
1. Arises from cell rests of dental lamina.
2. May also arise from extension of overlying basal cells.
CLINICAL AND RADIOGRAPHIC FEATURES
1. Any age with peak incidence in second and third
decades.
2. Positive Male predilection.
3. Most common in posterior mandible.
RADIOGRAPHIC FEATURES
4. Appears as radiolucency with well defined margins
usually unilocular.
5. May be multiple (Gorlin Syndrome).
OKC and Gorlin Goltz syndrome… its features……
odontogenic keratocyst = A cyst derived from the remnants (rests) of
the dental lmina, with a biologic behavior similar to a benign
neoplasm,
Clinical Features:
wide age range, peak occurance in 2nd and 3rd decades
more common in males than females
70-80% involve the mandible
typically asymptomatic
the cyst are multiple in 10% of cases
Treatment: surgical enucleation
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Prognosis: high rate of recurrence
dentigerous cyst
o An odontogenic cyst that surrounds the crown f an impacted tooth;
o caused by fluid accumulation between the reduced enamel
epithelium and the enamel surface,
o resulting in a cyst in which the crown is located within the lumen
and root(s) outside.
o 3 treatment options for Dentigerous cyst.
Treatment:
surgical enucleation
if a molar is involve, it is extracted
if premolar is involved, cyst is excised and ortho
treatment given
ODONTOGENIC KERATOCYST
HISTOPATHOLOGY
1. Thin friable wall, typically with minimal inflammation
2. Lining is stratified squamous epithelium, 6- 8 cells thick
3. Flat epithelium-connective tissue interface
4. Palisaded hyperchromatic cuboidal or columnar epithelial basal
cell layer
5. Flattened luminal parakeratotic cells in wavy or corrugated
appearance
6. Luminal layer may show orthokeratin
ODONTOGENIC KERATOCYST TREATMENT AND PROGNOSIS
1. Enucleation with peripheral osseous curettage or ostectomy,
2. this may be done in combination with Carnoy's solution or
3. cryotherapy.
4. Parakeratotic variant has a recurrence rate from 5 - 62%,
5. which may be due to:
o Friability of wall, leading to incomplete removal
o Satellite cysts
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o Increased mitotic activity of cystic epithelium
NEVOID BASAL CELL CARCINOMA SYNDROME
(Gorlin Syndrome)
1. Autosomal Dominant
2. Frontal and Temporoparietal Bossing
3. Hypertelorism
4. Mild Prognathism
5. Multiple Basal Nevi (often in non-sun exposed skin)
6. Palmer and Planter Pitting
NEVOID BASAL CELL CARCINOMA SYNDROME (Gorlin
Syndrome)
Bifid Ribs
Spina Bifida
Medullablastoma
Calcification of Falx Cerebri
Dysgenesis of Corpus Callosum
Multiple Odontogenic Keratocysts
GINGIVAL CYST OF THE NEWBORN
Small superficial keratin-filled cysts found on the alveolar
mucosa of infants.
CLINICAL FEATURES
Small whitish papules on the alveolar mucosa usually less than
2 mm in diameter.
HISTOPATHOLOGY
1. Flattened epithelial lining with a parakeratotic surface.
2. The lumen contains keratinaceous debris.
TREATMENT AND PROGNOSIS
Spontaneously involute as a result of the rupture of the cyst.
LATERAL PERIODONTAL CYST
1. A cyst arising in the lateral periodontal region
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2. in which an inflammatory origin (lateral radicular cyst) or
3. diagnosis of an odontogenic keratocyst has been excluded by
clinical and histological means.
It is believed to arise from
1. rests of the dental lamina or
2. proliferation of the reduced enamel epithelium along the root
surface.
LATERAL PERIODONTAL CYST CLINICAL AND RADIOGRAPHIC
FEATURES
Usually in patients over 30 years of age with a Male
predilection.
Most common in mandibular canine-premolar region.
Appears as a well-circumscribed radiolucency lateral to the
roots of vital teeth.
Multilocular variant consisting of a "grape like" cluster of small
cysts; have been termed Botryoid Odontogenic Cysts.
LATERAL PERIODONTAL CYST HISTOPATHOLOGY
1. Thin non-inflamed fibrous wall lined by a thin layer of squamous
epithelium.
2. May show areas of thickening composed of clear cells.
TREATMENT AND PROGNOSIS
Conservative enucleation with care to conserve adjacent
periodontal ligaments. Recurrence is unusual but has been
reported with the Botryoid variant.
GINGIVAL CYST OF THE ADULT
Represents the soft tissue counterpart of the lateral periodontal
cyst being derived from rests of the dental lamina.
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The diagnosis of this cyst should be restricted therefore to
lesions with the same histopathologic features as the lateral
periodontal cyst.
CLINICAL FEATURES
Most common in mandibular canine-premolar region, invariably
found on the facial gingiva or alveolar musosa.
Most common in fifth and sixth decades of life.
Appear as painless dome like swellings which may cause
superficial cupping of bone.
GINGIVAL CYST OF THE ADULT
HISTOPATHOLOGY
Same as the lateral periodontal cyst. Consists of thin flattened
epithelial lining with or without areas of focal thickening that
contain clear cells.
TREATMENT AND PROGNOSIS
Prognosis is excellent with simple surgical excision.
CALCIFYING ODONTOGENIC CYST
(Gorlin Cyst)
Uncommon lesion, that demonstrates variable histopathologic
appearance and clinical behavior.
Some appear to represent non-neoplastic cysts.
Others designated as Epithelial Odontogenic ghost cell
Tumours.
These have no cystic features, may be infiltrative or even
malignant and are considered neoplasms.
May be associated with other odontogenic tumours such as
odontomas.
CALCIFYING ODONTOGENIC CYST
(Gorlin Cyst)
CLINICAL AND RADIOGRAPHIC FEATURES
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Predominantly intraosseous, but may be peripheral.
Appear in equal frequency in the maxilla and mandible, most
commonly in the anterior area.
Any age, but mostly in second and third decades of life.
Usually appears as a unilocular, well defined radiolucency with
radiopaque structures within the lesion.
CALCIFYING ODONTOGENIC CYST
(Gorlin Cyst)
HISTOPATHOLOGY
The cystic form compromises 86-98% of the lesions.
Consists of lining epithelium, 4 - 10 cell layers thick. The basal
cells may be cuboidal or columnar, similar to ameloblasts.
The overlying layer of loosely arranged epithelium may
resemble the stellate reticulum.
(Gorlin Cyst)
The ghost cell is the characteristic feature. These are
eosinophilic epithelial cells characterized by loss of the nuclei
with preservation of the basic cell outline.
Areas of calcification may be seen representing dysplastic
dentin formation.
20% are associated with odontomas.
The solid variant comprises 2 - 16% and most are
extraosseous, histopathologically they resemble
ameloblastomas but also contain ghost cells and dysplastic
dentin.
(Gorlin Cyst)
TREATMENT AND PROGNOSIS
The prognosis for the cystic variant is good after simple
enucleation.
The peripheral neoplastic variant has the same prognosis as a
peripheral ameloblastoma with little chance for recurrence after
excision.
GLANDULAR ODONTOGENIC CYST
10
Also known as the sialo-odontogenic cyst first described in
1987. Shares features with the Botryoid Odontogenic Cyst and
muco-epidermoid tumour.
CLINICAL AND RADIOGRAPHIC FEATURES
Most common in anterior mandible.
May occur at any age with a mean age of 50.
No Gender predilection.
Appears mostly as a multilocular radiolucency with well defined
sclerotic borders.
GLANDULAR ODONTOGENIC CYST
HISTOPATHOLOGY
The lining consist of squamous epithelium of varying thickness.
The superficial layer of cells tend to be cuboidal having an
irregular surface on which cilia may be noted. These cells
surround cystic mucous filled spaces.
Mucous cells are also scattered along the lining.
GLANDULAR ODONTOGENIC CYST
TREATMENT AND PROGNOSIS
Enucleation with peripheral curettage or ostectomy.
25% recurrence rate has been reported, therefore long term
follow-up is essential.
INFLAMMATORY CYST
Periapical Cyst
(Radicular Cyst, Apical Periodontal Cyst)
Lateral Radicular Cyst
Residual Radicular Cyst
Paradental Cyst
These cysts may arise from inflammatory stimulus to epithelium
at the apex of a non vital tooth, or adjacent to a lateral canal of
non vital tooth.
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INFLAMMATORY CYST
The source of the epithelium is usually rests of Malassez, but
may be crevicular epithelium, sinus lining or lining of fistulous
tracts.
Inflammation within paradental follicular tissue of impacted
teeth may give rise to the paradental cyst.
Inflammatory tissue not curetted at time of tooth removal may
give rise to an inflamed residual radicular cyst.
INFLAMMATORY CYST
GROWTH OF INFLAMMATORY CYSTS
These cysts represent a fibrous connective tissue wall lined by
epithelium with a lumen containing fluid and cellular debris.
As epithelium desquamates into the lumen, the protein content
rises and fluid enters in an attempt to equalize the osmotic
pressure and enlargement occurs.
INFLAMMATORY CYST
HISTOPATHOLOGY
These cysts are lined by stratified squamous epithelium which
may show hyperplasia or spongiosis. The lumen is filled with
fluid and cellular debris.
Linear or arch shaped calcifications known as Ruston bodies
may be present within the lining.
Dystrophic calcification, cholesterol clefts and hemosiderin
pigmentation may be seen.
The wall consists of dense fibrous connective tissue with a
mixed inflammatory infiltrate.
TREATMENT AND PROGNOSIS
RADICULAR CYST
Extraction or endodontic treatment of tooth with or without
enucleation/marsupialization of cyst.
RESIDUAL CYST
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Enucleation and curettage.
PARADENTAL CYST
Enucleation and curettage with extraction of impacted tooth.
Cysts of inflammatory origin will not recur after appropriate
management, however fibrous scars are possible.
ODONTOGENIC CYSTS AND TUMORS
(Part 2)
ODONTOGENIC TUMORS
Lesions derived from epithelial or mesenchymal elements, or both,
that are part of the tooth-forming apparatus.
They are therefore found exclusively in the mandible, maxilla and on
rare occasions,the gingiva.
ODONTOGENIC TUMORS
Like normal odontogenesis, demonstrate varying inductive
interactions between odontogenic epithelium and odontogenic
mesenchyme. Some are composed only of odontogenic epithelium.
Others, sometimes referred to as mixed tumors, are composed of
odontogenic epithelium and mesenchymal elements.
A third group are composed principally of odontogenic mesenchyme.
EPITHELIAL TUMORS
Ameloblastoma
Squamous Odontogenic Tumor
Calcifying Epithelial Odontogenic Tumor
Clear Cell Odontogenic Tumor
Adenomatoid Odontogenic Tumor
MESENCHYMAL TUMORS
Odontogenic Myxoma
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Odontogenic Fibroma
Cementoblastoma
Cementifying Fibroma
MIXED ODONTOGENIC TUMORS
Ameloblastic Fibroma
Ameloblastic Fibro-Odontoma
Odontoameloblastoma
Odontoma
AMELOBLASTOMA
Most common odontogenic tumor after the odontoma
Arises from ondontogenic epithelium
Potential sources include odontogenic rests (rests of Malassez,
Rests of Serres), reduced enamel epithelium, and the epithelial
lining of odontogenic cysts
CLINICAL AND RADIOGRAPHIC FEATURES
Most common in 4th and 5th decades
No apparent gender predilection
May occur anywhere, but most common in the mandibular
ramus; in the maxilla, the molar area is more commonly
affected
Extraosseous (peripheral) variant of ameloblastoma are found
in the gingiva and have been described in the buccal mucosa
Usually asymptomatic, discovered during routine radiographic
examination or because of jaw expansion or occasional tooth
movement
Radiograph: Appear as unilocular or multilocular radiolucencies
with well defined sclerotic margins (Desmoplastic variant
typically has ill defined margins)
Tooth movement and/or root resorption may also be seen
May be associated with an impacted tooth
14
HISTOPATHOLOGY
Numerous histologic patterns have been described
Some may exhibit a single subtype; others may demonstrate
several histologic patterns within the same lesion
FOLLICULAR AMELOBLASTOMA
Most common type
Composed of islands of epithelium that resemble enamel
organ epithelium in a fibrous connective tissue stroma
Epithelial nests consist of a core of loosely arranged angular
cells resembling the stellate reticulum, surrounded by a single
layer of tall columnar ameloblast like cells
The nuclei of these cells are located at the opposite pole of the
basement membrane (reversed polarity)
Central cystic degeneration may be seen within the follicular
islands
PLEXIFORM AMELOBLASTOMA
Consists of long anastomosing cords or sheets of columnar
ameloblast like cells surrounding loosely arranged angular
stellate reticulum like cells
Supporting stroma tends to be loosely arranged and vascular
Cyst formation is relatively uncommon in this variant
ACANTHOMATOUS AMELOBLASTOMA
Exhibits squamous metaplasia, often with keratin formation in
the central portion of the epithelial islands of a follicular
ameloblastoma
May be confused with a squamous cell carcinoma or
squamous odontogenic tumor
15
GRANULAR CELL AMELOBLASTOMA
Exhibits cells with prominent cytoplasmic granularity
Has been thought by some authors to be more aggressive with
a higher recurrence rate, but this has not been substantiated
DESMOSPLASTIC AMELOBLASTOMA
Exhibits islands and cords of odontogenic epithelium in a
densely collagenized stroma
More common in the anterior maxilla
Radiograph: May have ill defined borders.
BASALOID (Basal Cell) AMELOBLASTOMA
Uncommon subtype
Composed of nests of uniform basaloid cells with no stellate
reticulum resembling a basal cell carcinoma
SOLID OR MULTICYSTIC AMELOBLASTOMAS
May exhibit any or all of the histologic patterns discussed
More aggressive, requiring extensive treatment as opposed to
their unicystic counterpart
Higher recurrence rate if treated with curettage only
UNICYSTIC AMELOBLASTOMAS
Exhibit a major cystic space in which there may be intraluminal
or mural growth
May also arise within the lining of odontogenic cysts
More common during 2nd decade of life
Less aggressive than multicystic variant with a much lower
recurrence rate if treated with curettage only
SOLID OR MULTICYSTIC AMELOBLASTOMAS
TREATMENT AND PROGNOSIS
16
Should be treated with marginal resection of up to 1 cm, which
may consist of en-bloc resection or even resection (due to the
high recurrence rate: 50 - 90%) with enucleation and curettage
only
Recurrence rate with marginal resection is up to 15%, therefore
the patient should be placed on long term follow-up
UNICYSTIC AMELOBLASTOMASTREATMENT AND PROGNOSIS
Usually diagnosed microscopically after enucleation of a
presumed cyst
This treatment is usually adequate, but the patient should be
placed on long term follow-up since recurrence rates of 10-20%
have been reported
TREATMENT AND PROGNOSIS
Peripheral Ameloblastoma is treated with local surgical excision
Recurrence rate of 25% has been reported, but further local
excision almost always results in a cure
Ameloblastomas may rarely metastasize (less than 1%) to
distant locations and local lymph nodes, the most common site
being the lungs
Malignant Ameloblastomas: Primary and metastatic lesions are
well differentiated
Ameloblastic Carcinomas: Primary and metastatic lesions
show poor differentiation with cytologic atypia and mitotic
figures
SQUAMOUS ODONTOGENIC TUMOR
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Rare odontogenic neoplasm
Thought to arise from the rests of Malassez
CLINICAL AND RADIOGRAPHIC FEATURES
Patient age range: 11 - 67 years
Mean age of 40 years
No gender predilection
Appear in equal frequency in the maxilla and mandible within
the alveolar processes
Usually appear as an asymptomatic or mildly painful gingival
swelling often with mobility of associated teeth
20%of affected patients have multiple lesions
Radiograph: Appear as a well circumscribed often semilunar or
triangular lesion associated with the roots of teeth
SQUAMOUS ODONTOGENIC TUMOR HISTOPATHOLOGY
Islands of bland appearing squamous epithelium in a fibrous
connective tissue stroma
Areas of microcysts and keratin formation may be seen within
the epithelial islands
Areas of dystrophic calcifications may be seen
TREATMENT AND PROGNOSIS
Conservative enucleation and curettage is usually curative with
a low recurrence rate
CALCIFYING EPITHELIAL ODONTOGENIC TUMOR
(Pindborg Tumor)
18
Uncommon odontogenic tumor
Origin unknown - stratum intermedium has been mentioned as
a possibility
CLINICAL AND RADIOGRAPHIC FEATURES
Mean age of 40 years
No gender predilection
Twice as common in the mandible with a predilection for the
molar, ramus area
) CLINICAL AND RADIOGRAPHIC FEATURES
Most commonly present as a slow growing painless swelling
Radiograph: May present as a unilocular or multilocular
radiolucency with scalloped margins; areas of calcification may
be present
Usually associated with impacted tooth
Peripheral variants have been reported
HISTOPATHOLOGY
Sheets of large polygonal epithelial cells in a fibrous stroma
Nuclear pleomorphism may be evident
Large deposits of extracellular material that stain positive for
amyloid with congo red are also seen
Concentric calcifications called Liesegang rings may also be
seen
Some may demonstrate optically clear cells
CALCIFYING EPITHELIAL ODONTOGENIC TUMOR(Pindborg
Tumor)
TREATMENT AND PROGNOSIS
Have a limited invasive potential therefore local excision with
limited margins is indicated
20% recurrence rate has been reported
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CLEAR CELL ODONTOGENIC TUMOR(Carcinoma)
Rare odontogenic tumor with potential for lymphatic or
pulmonary metastases
Origin unknown
CLEAR CELL ODONTOGENIC TUMOR(Carcinoma)
CLINICAL AND RADIOGRAPHIC FEATURES
Most cases reported in women over age 60
Both maxilla and mandible have been involved
May present as asymptomatic or painful bony swelling
Radiograph: Unilocular or multilocular radiolucency with ill
defined margins
CLEAR CELL ODONTOGENIC TUMOR(Carcinoma)
HISTOPATHOLOGY
Nests of epithelial cells with a clear or faintly eosinophilic
cytoplasm separated by thin strands of hyalanized material;
peripheral cells may demonstrate palisading
Some consider this tumor to be a clear cell variant of the
ameloblastoma
CLEAR CELL ODONTOGENIC TUMOR(Carcinoma)
HISTOPATHOLOGY
Must be differentiated from CEOT with clear cell component, central
mucoepidermoid carcinoma and metastatic clear cell carcinomas
such as renal cell carcinoma
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CLEAR CELL ODONTOGENIC TUMOR
(Carcinoma) TREATMENT AND PROGNOSIS
Tumors demonstrate aggressive local behavior and potential
lymphatic and pulmonary metastases and therefore should be
treated with extensive resection
ADENOMATOID ODONTOGENIC TUMOR
Represents 3 - 7% of odontogenic tumors
Believed to arise from the enamel organ epithelium
Used to be classified as a variant of the ameloblastoma
"adenoameloblastoma" but now recognized as a separate entity
ADENOMATOID ODONTOGENIC TUMOR CLINICAL AND
RADIOGRAPHIC FEATURES
2/3 occur between 10 - 19 years of age
2/3 occur in females
2/3 occur in anterior maxilla
Peripheral variant has been reported
Mostly associated with an unerupted tooth especially the
maxillary canine
Radiograph: Asymptomatic radiolucency which may or may
not be associated with an unerupted tooth
Usually exhibits fine calcifications
ADENOMATOID ODONTOGENIC TUMOR
HISTOPATHOLOGY
21
Appear as a proliferation of polyhedral and spindle shaped
epithelial cells
Rosettes or duct like structures are usually present hence the
name adenomatoid
Areas of calcification representing abortive enamel formation
may be seen
Some tumors contain large areas of calcification thought to be
cementoid or dentoid material, therefore some consider this
tumor to be a mixed tumor
TREATMENT AND PROGNOSIS
Because of this tumor’s completely benign behavior,
conservative enucleation is all that is required
ODONTOGENIC MYXOMA
Arise from mesenchymal odontogenic elements and mimic the
dental pulp
CLINICAL AND RADIOGRAPHIC FEATURES
Occur in young adults; Mean age - 30 years
No gender predilection
Occur in equal frequency in the mandible and maxilla
May demonstrate rapid growth, usually asymptomatic
expansion of bone
Radiograph: Unilocular or multilocular with often irregular
scalloped margins; may also demonstrate many thin trabeculae
or soap bubble appearance
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ODONTOGENIC MYXOMA HISTOPATHOLOGY
Exhibits loosely arranged stellate and spindle shaped cells in
an abundant, loose myxoid stroma; odontogenic epithelial rests
may or may not be seen
Some have a tendency to form collagen fibers and have been
designated as fibromyxomas
TREATMENT AND PROGNOSIS
Tumors may be difficult to enucleate due to their loose
consistency, therefore surgical excision is indicated
Recurrence rates of up to 25% reported
Some may exhibit marked cellularity and atypia; and have a
more aggressive course (myxosarcomas)
ODONTOGENIC FIBROMA
Rare tumor of mesenchymal origin
May occur centrally or in the periphery
ODONTOGENIC FIBROMA CLINICAL AND RADIOGRAPHIC
FEATURES
All age groups: Mean age of 40 years
Marked female predilection
60% of cases reported in anterior maxilla
Usually asymptomatic but may cause localized bony expansion
or loosening of teeth
ODONTOGENIC FIBROMA CLINICAL AND RADIOGRAPHIC
FEATURES
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Radiograph: Well defined unilocular lesions often associated
with apices of erupted teeth
Larger lesions tend to be multilocular with a sclerotic border
causing root divergence and resorption
Peripheral variant clinically mimics the fibroma
HISTOPATHOLOGY
Two subtypes have been described:
Simple odontogenic fibroma which is composed of stellate
fibroblasts with fine collagen fibrils in which rests of
odontogenic epithelium and dystrophic calcification may or may
not be present
HISTOPATHOLOGY
Two subtypes have been described:
WHO odontogenic fibroma which consists of fairly cellular
fibrous connective tissue, odontogenic epithelium strands and
nests throughout the lesions with occasional calcifications
composed of cementoid or dentoid material
Variant: Granular cell odontogenic fibroma or Granular cell
odontogenic tumor
Consists of large eosinophilic granular cells with cords and
islands of odontogenic epithelium in which some areas of
calcification may be present
TREATMENT AND PROGNOSIS
Treated with enucleation and curettage
Only a few recurrences have been documented
24
CEMENTOBLASTOMA
(True Cementoma)
Rare benign odontogenic neoplasm
Arises from the cementoblast
CLINICAL AND RADIOGRAPHIC FEATURES
Occurs predominantly in 2nd & 3rd decades of life; typically
before 25 years of age
No gender predilection
Most common in the posterior mandible
Intimately associated with the root of a tooth which remains vital
Radiograph: Opaque lesion that replaces the root of a tooth. It
is usually surrounded by a radiolucent ring
HISTOPATHOLOGY
Appears as a conglomeration of variably mineralized cementum
like material with reversal lines
Intervening soft tissue contains cementoblasts
Cementoclasts are also evident
TREATMENT AND PROGNOSIS
Excision with extraction of the associated tooth
Recurrence is not seen
CEMENTIFYING FIBROMA(Cemento-ossifying Fibroma)
May be impossible to separate from the ossifying fibroma
Only separating feature is the microscopic presence of bone or
cementum which is subjective
CLINICAL AND RADIOGRAPHIC FEATURES
Any age: Mainly adults around age 40
Positive female predilection
25
More common in the mandible
Radiograph: Varies from a lucent, mixed to opaque lesion with
well defined sclerotic margins
HISTOPATHOLOGY
Consists of a fibroblastic stroma in which cellularity may be
high
Islands of cementum surrounded by eosinophilic cementoid and
cementoblasts are distributed throughout the lesion
TREATMENT AND PROGNOSIS
Enucleation is all that is required
Recurrence is uncommon
AMELOBLASTIC FIBROMA AMELOBLASTIC FIBRO-ODONTOMA
True mixed tumors in which the epithelial mesenchymal
elements are both neoplastic
Both of these tumors are similar in all regards except for the
presence or absence of an odontoma
CLINICAL AND RADIOGRAPHIC FEATURES
Children and young adults: Mean age - 12 yrs
Slightly more common in males
Any region may be affected but mandibular molar area is the
most frequently affected area
May be asymptomatic or present as an expansile bony lesion
Radiograph: Well circumscribed unilocular or multilocular
radiolucencies usually surrounded by a sclerotic border
50%of the time they are associated with the crown of an
impacted tooth
Differ from dentigerous cysts in the level of attachment to the
tooth which is typically lower than the cemento-enamel junction
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An opaque focus appears within the ameloblastic fibro-
odontoma owing to the presence of an odontoma
Ameloblastic fibroma is completely lucent
HISTOPATHOLOGY
Resembles the pulp in the general absence of collagen
Mainly primitive appearing myxoid tissue
Distributed through the mesenchyme are strands of
odontogenic epithelium 2 - 3 layers thick, in addition to islands
that resemble the epithelial portion of the follicular
ameloblastoma
HISTOPATHOLOGY
In the ameloblastic fibro-odontoma, cells in one or more of the
foci continue the differentiation process to produce enamel and
dentin
TREATMENT AND PROGNOSIS
Enucleation and curettage is usually curative, thought some
authors report a recurrence rate of 20% for the ameloblastic
fibroma and advocate a more aggressive surgical excision
A malignant counterpart, the Ameloblastic Fibrosarcoma, has
been reported to arise de-novo or from pre-existing or recurrent
fibrosarcomas
This is a locally aggressive lesion with metastatic potential,
therefore should be resected
ODONTOAMELOBLASTOMA
Extremely rare odontogenic tumor
Was formerly called the Ameloblastic Odontoma and confused
with the Ameloblastic Fibro-odontoma
CLINICAL AND RADIOGRAPHIC FEATURES
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Appears to occur more often in the mandible of younger
patients
Pain, delayed eruption of teeth, and bony expansion may be
noted
Radiograph: Tumor shows a radiolucent, destructive process
that contains calcified structures that may resemble a
compound or complex odontoma
ODONTOAMELOBLASTOMA HISTOPATHOLOGY
Epithelial portion has features of an ameloblastoma, most often
of the plexiform or follicular pattern
Intermingled within is immature or more mature dental tissue
similar to a compound odontoma or conglomerate masses of
enamel, dentin and cementum as seen in complex odontomas
ODONTOAMELOBLASTOMA
TREATMENT AND PROGNOSIS
Tumor appears to have the same recurrence potential as an
ameloblastoma and therefore should be treated similarly
ODONTOMA
Most common odontogenic tumor
May appear as numerous miniature or rudimentary teeth
known as compound odontomas, or
Amorphous conglomerations of hard tissue known as complex
odontomas
ODONTOMA
CLINICAL AND RADIOGRAPHIC FEATURES
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Most are detected in the first two decades of life; Mean age at
diagnosis - 14 years
No gender predilection
Maxilla is affected slightly more than the mandible with
compound odontomas showing a tendency for the anterior jaws
and complex odontomas for the posterior jaws
CLINICAL AND RADIOGRAPHIC FEATURES
Radiograph: Compound odontoma presents as a collection of
tooth-like structures of varying size and shape surrounded by a
narrow radiolucent zone
Complex odontoma presents as a calcified mass with the
radiodensity of tooth structure, surrounded by a narrow
radiolucent rim
An unerupted tooth may be associated with the odontoma
A developing odontoma may show little calcification and
appear as a well circumscribed radiolucency
HISTOPATHOLOGY
Compound odontomas consist of multiple structures resembling
small single rooted teeth, contained in a loose fibrous matrix
Complex odontomas consist largely of mature tubular dentin
TREATMENT AND PROGNOSIS
Treated by simple local excision and do not recur
-The stages:
1. The bud stage:
-epithelial cells from the dental lamina bud off and begin
forming the dental enamel organ for each primary &
succedaneous tooth.
2. The cap stage:
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-continued proliferation of the epithelium into the
ectomesenchyme with the formation of the dental papilla
and follicle.
-the dental papilla is the formative organ of dentin and
pulp.
-dental papilla + dental follicle + dental organ = tooth
germ
3. Bell stage:
-tooth germ becomes separated from the oral epithelium
-differentiation into 4 components: inner enamel
epithelium, outer enamel epithelium, stellate reticulum, &
stratum intermedium)
-the inner enamel epithelium assumes the dominant
inductive role.
4. Crown stage:
-the inner enamel epithelium induces the odontoblasts of
the dental papilla to lay down dentin.
-ameloblasts can now secrete the enamel matrix
-as enamel matrix is laid down, the stellate reticulum
collapses and the odontogenic epithelium is referred to as
the reduced enamel epithelium
-inner & outer enamel epithelium continue to proliferate in
an apical direction to form Hertwig’s epithelial root sheath
and the remnants of this root sheath persist within the
PDL space as the rests of Malassez
II. Odontogenic Cysts
-By definition, an odontogenic cyst is a pathologic cavity in bone or
soft tissue, which is lined by epithelium of odontogenic origin. This
epithelial lining may be derived from the dental lamina, dental organ,
reduced enamel epithelium, or rests of Malassez.
-2 classifications: inflammatory & developmental
A. Inflammatory odontogenic cysts
1. Apical periodontal cyst
-the most common of all odontogenic cysts
-infection, inflammation, or pulpal necrosis are
responsible for it’s origin.
-always assoc. with a non-vital tooth
-symptoms may include pain, swelling, drainage,
and tooth mobility.
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-origin: Hertwig’s epithelial root sheath
-txmnt: endo or extraction with curettage of the
socket
2. Residual cyst
-a cyst that persists following the extraction of a
tooth
-origin: may have originally been an apical
periodontal cyst, periapical granuloma, or a
dentigerous cyst
-txmnt: surgical exploration and thorough curettage
3. Paradental cyst (Buccal bifurcation cyst)
-origin: reduced enamel epithelium
-presents as a buccal swelling adjacent to a molar
tooth (mand 1st molar most common in children,
mand 3rd molar most common in adult).
-assoc. with an enamel projection in the area of root
bifurcation
-occl radiograph will show lingual displacement of
the tooth
-txmnt: soft tissue curettage with perio f/u or extr of
tooth
B. Developmental odontogenic cysts
1. Dentigerous cyst
-the most common developmental cyst
-always assoc. with the crown of an unerupted tooth
(usually a 3rd molar)
-can cause root resorption, tooth displacement, and
pain
-on radiograph, see a well demarcated unilocular
RL, surrounding the crown of an impacted tooth.
-histo: an empty or clear fluid filled cyst, which is
lined by thin non-keratinized epith.
-txmnt: extr with curettage or marsupialization.
-rare malignant transformation, can develop into an
ameloblastoma
2. Eruption cyst
-a variant of the dentigerous cyst caused by fluid or
blood b/w the crown of an erupting tooth and the
surface mucosa.
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-lesions appear as bluish-purple, dome-shaped
swellings at the crest of the alveolar bone.
-txmnt: none required
3. Lateral periodontal cyst
-origin: post-functional dental lamina or rests of
Malassez
-a lesion of adulthood---avg. age = 50
-most common location: mand PM/canine area
(67%); max lateral (33%). Adjacent teeth are vital.
-radiograph reveals a well-circumscribed unilocular
mid-root RL
-txmnt: conservative surgical excision/preserve
adjacent tooth structure
-multilocular-variant is termed botryoid (“grape-like”)
odontogenic cyst
4. Gingival cyst of infancy and gingival cyst of adult
-origin: post-functional dental lamina rests
-childhood lesions appear as multiple smooth white
nodules on the alveolar ridge, often present at birth.
Do not confuse with Epstein’s Pearls (midline of
hard palate) or Bohn’s nodules (hard/soft palate
junction).
-the cysts are filled with keratin debris
-txmnt: none required
-some pathologists consider the adult lesion to be
the soft tissue counterpart of the lateral periodontal
cyst.
5. Odontogenic keratocyst (OKC)
-the most common multilocular radiolucency; they
may displace teeth, cause root resorption, thin the
bony cortex, and on rare occasions, perforate the
cortical bone.
-Peak incidence: 3rd-4th decade of life (male
predilection)
-mandible affected 2x as often as maxilla---with the
angle & 3rd molar area being the most common
sites.
-25% will be multilocular, and about 40% will be
assoc. with an impacted tooth.
-histo:
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a. corrugated (wavy) keratin lining
b. keratin is parakeratin
c. 6-10 cell layers thick
d. basal cell layer exhibits palisades (like a
picket fence)
e. basal cell layers are dark (hyperchromatic
nuclei)
-OKC is a major component of the Nevoid Basal
Cell Carcinoma
-txmnt: from enucleation with curettage to en bloc
resection
6. Keratinizing odontogenic cyst (KOC)
-originally described as the “orthokeratinized”
variant of the OKC
-almost always presents as a unilocular RL assoc.
w/ an impacted 3rd molar
-no hyperchromatism or palisaded arrangement of
cells.
7. Calcifying odontogenic cyst (Gorlin cyst)
-expansile intraosseous lesion
-bi-modal peak incidence: 2nd & 7th decades of life
-see radiopaque flecks, masses or tooth-like
densities
-** this is the only odontogenic cyst with
radiopacities as a component
-ghost cells in epithelial lining
-txmnt: surgical excision
-the aggressive non-cystic variant is the epithelial
odontogenic ghost cell tumor (seen in odontogenic
tumor section)
8. Glandular odontogenic cyst
-called this b/c of duct-like structures w/in the wall
9. Carcinoma arising in an odontogenic cyst
-rare event; most are sq. cell carcinomas
-see ragged, irregular borders which may be the
clue to malignancy
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