1. Odontogenic tumors III
Mixed odontogenic tumors
By:Prof Dr.:Nadia Lotyf
Odontogenic epithelium with odontogenic ectomesenchyme with or without
dental hard tissue formation
In this group of odontogenic tumor, both epithelium and mesenchymal
components are neoplastic. These include:
1- Ameloblastic fibroma and Ameloblastic fibro-odontomas.
2- Adenomatoid odontogenic tumor.
3- Odontoms
1-Ameloblastic fibroma
Both the epithelium and mesenchyme are part of the tumor.
Clinical Feature
Age: It is considered a tumor of childhood and adolescence as it occurs in the first and second
decades of life.
Sex: A slight male predilection has been noted.
Site: The most common location for the tumor is the posterior mandible, followed by the
posterior maxilla.
O Patients often present with painless swelling of the jaw and the lesion may affect the
normal eruption of teeth in the area.
O An impacted tooth may be associated with the tumor in most of the cases.
O Small lesions are asymptomatic and detected on routine dental radiographs
Radiographic Feature
O Unilocular to multilocular radiolucency with well-defined radiopaque margin
O Often associated with an unerupted tooth
Microscopic Feature:
Ameloblastic fibroma is composed of 2 main elements :
1- Connective tissue background:
Looks like dental papilla, composed of spindled and angular cells with little collagen.
2- The epithelial component
Is made up of thin cords or small nests of odontogenic epithelium. Larger nests may
show a central area of stellate reticulum.
Juxta epithelium hyalinization may be found.
The tumor may be surrounded by fibrous capsule.

2. Differential Diagnosis
• Ameloblastoma
• Dentigerous cyst
• Odontogenic keratocyst
• Odontogenic myxoma
• Central giant cell granuloma
Treatment:
O Surgical excision.
O The recurrence rate is low.
O The possibility of malignant transformation of ameloblastic fibroma into
ameloblastic fibrosarcoma is well documented.
Ameloblastic fibrosarcoma
It is a rare malignant odontogenic tumor regarded as the malignant counterpart of
ameloblastic fibroma or arises de novo.
It is characterized by a benign epithelial component within a malignant fibrous stroma.
It is rapidly progressive, and fatal.
It is found in the posterior mandible.
Age: 26-year . Males
Histopathologic Feature
1- Benign epithelial component looks like that of ameloblastic fibroma.
2- Mesenchymal component which showed areas exhibiting stellate-shaped cells. These
cells which exhibit pleomorphism with hyperchromatic nuclei and mitotic activity.
Ameloblastic fibro-odontoma
The ameloblastic fibro-odontoma, represents a hamartoma.
Some investigators believe that ameloblastic fibro-odontoma is an immature complex
odontoma.
Clinical Feature

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Age: in children ear10 y
Site: posterior regions of the jaws (mandible= maxilla).
It is asymptomatic and detected when radiograph is taken to determine reason for
failure of tooth to erupt.
Radiographic Feature
This tumor shows radiographic similarities with ameloblastic fibroma, with variable degree
of radiopacities (calcified martials).
Radiopacity may appear as:
1. Multiple small radiopacity or
2. Solid mass.
Un unerupted, tooth is present at the margin of the tumor.
Histopathologic Feature
It consists of
1- Soft tissue component: Identical to ameloblastic fibroma.
2- Calcifying component: Consists of foci of enamel and dentin.
It has little chance of recurrence or malignant transformation.
2-Adenomatoid Odontogenic Tumor
It is a mixed odontogenic tumor characterized by:
 epithelium with duct like structure
 Varying degrees of inductive change in the connective tissue ,so it may produce
dentinoids
 Despite of its name it has no glandular element
Represents less than 10% of odontogenic tumors
It was considered as a type of ameloblastoma, yet its biologic behavior allows for distinction
from ameloblastoma.
Clinical Feature
• Age: young patients, most of the cases are diagnosed in the second decade.
• Site: It has a predilection for the anterior region of the jaws and is found twice as often in
the maxilla than in the mandible.
•Sex: Females are affected about twice as often as males.

4. Most adenomatoid odontogenic tumors are small, rarely exceeding 3 cm in diameter.
Asymptomatic and may produces expansion of alveolar bone .
rarely occurs in the gingiva (peripheral)
• May produce root divergence of adjacent teeth
Radiographic Feature
• The lesion appears as well defined, unilocular radiolucency, often adjacent to crown of
unerupted, tooth (usually a canine)
• Opaque foci may be scattered within the radiolucency giving a “snowflake” or “salt and
pepper” pattern.
Snow flake
Microscopic Feature
 The tumor is composed of spindle-shaped epithelial cells that form sheets, strands, or
whorled masses of cells in a few fibrous stroma.
 Tubular or duct-like structures are characteristic for the adenomatoid odontogenic
tumor, which consists of a central space surrounded by a layer of columnar or
cuboidal epithelial cells whose nuclei exhibit reverse polarization .
duct-like structures
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Whorled spindleshaped epithelial cells
Convoluted bands: A whorled mass of columnar cells with a thin layer of
homogenous eosinophilic material between two rows of columnar cells.

5. Convoluted bands
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foci of calcification
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Small foci of calcification are found throughout the tumor representing dentin ,
cement or enamel which is due to inductive influence of the epithelium on connective
tissue
Tumor may be solid or cystic i.e, the tumor develops in the wall of a cyst.
The tumor is surrounded by thick fibrous capsule.
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Differential Diagnosis
Dentigerous cyst
Odontogenic keratocyst
Calcifying odontogenic cyst.
Calcifying epithelial odontogenic tumor
Treatment
As the lesion is encapsulated, it separates easily from the surrounding bone. So, enucleation
is curative.
3-Odontomas
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These lesions are accepted as hamartomas.
Odontomas are the most common odontogenic tumors. It is equal to all other
odontogenic tumors combined.
Odontomas are defined as: A developmental malformation that contains fully formed enamel ,
dentine , cementum and pulp.
Odontomas present centrally within the jaws in one of two forms:
Compound odontomas:
In which multiple small tooth like structures exist.
Complex odontomas:
In which irregular masses of dentin and enamel are present with no anatomic resemblance to
a tooth.
Clinical feature
tooth like structures
Compound odontoma

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Age: It is found in children and young adolescents in whom dental development is
still taking place.
Small lesions is asymptomatic and discovered incidentally
Large lesions presented as jaw expansion
Usually associated with retained primary tooth.
Site: Compound odontomas are predominantly seen in the anterior maxilla.
Complex odontomas are typically seen in the posterior maxilla or mandible.
Radiographic feature
Early stage: well defined radiolucent with radiopaque foci and surrounded by radiopaque
rim.
usually associated with an impacted tooth
Mature stage : appears radiopaque with radiolucent rim
O
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Compound odontomes, consists of a large number of denticles in which the dental
tissues are arranged in a normal pattern. (Looks like a bag of teeth).
Complex odontomes, there is progressive formation of radiopaque mass of a nodular
nature
Compound
odontoma
Complex odontoma
Histopathologic feature
Early stage
similar to that of an ameloblastic fibroma
Later,
hard tissue formation start to develop:
In compound odontome
Consists of a number of denticles in a fibrous tissue .
The denticles are made of regular enamel dentine, cementum & pulp arranged as in normal
teeth

7. In complex odontome
Consists of a mass of irregularly arranged but well formed enamel , dentine , cementum &
pulp
Dentine forms the bulk of the lesion , enamel that is well calcified appears as empty spaces ,
while cementum is often present at the periphery of the mass
Differential diagnosis :
complex odontomas are similar to
1. focal sclerosing osteomyelitis
2. osteoma
3. periapical cemental dysplasia
4. ossifying fibroma
5. cementomas
Treatment
• Conservative excision/curettage
Prognosis
• Excellent