Squamous Odontogenic tumour

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Oral pathology lec#10


Last time we started talking about the benign odontogenic tumors ( epithelial lesions without odontogenic mesenchyme ) and the 1st one was the ameloblastoma

In this lecture we'll continue all other types of odontogenic tumors .

Squamous Odontogenic tumour

  • Clinically :

  • Young adults

  • Anterior to molars

  • Painless swelling , ± Tenderness & loosening of associated teeth

  • Origin : rest cells of masslez (odontogenic epithelium )

  • Radiogragh : its like a severe periodontal disease or lateral periodontal cyst .

Unilocular , semilunar radiolucency ( could be triangular in shape sometimes ) present between the roots of the teeth .

As the calcification increases the radio-opacity increases inside the tumor.

  • When you take a biopsy you could notice that its solid/hardened tissue.

  • Hist:

  • Elongated and rounded islands of normal appearing stratified squamous epithelium .

  • Sourrounded by fibrous tissue trauma

  • Inside the epithelial islands , Keratin, microcysts spaces, calcified structures could be found .

Calcifying epithelial odontogenic tumour (Pindborg tumour)

  • Clinically :

  • Rare ( less than 1% of these tumors )

  • Mainly occur in Adults

  • Slowly enlarging painless mass ( as its benign )

  • 2/3 of the cases are found in the Mandible,in the molar & premolar region

  • Its mainly a central tumor(within the bone) but In some cases , its formed inside the gingiva so it's called peripheral Calcifying epithelial odontogenic tumour .

  • Prognosis :

It’s a benign but locally invasive/infiltrative neoplasm like the ameloblastoma , but it has a lower recurrence rate ( less than 20% )

  • In radiogragh :

  • It can't be differentiated easily ( irregular radiolucent area )

  • Can be multilocular or unilocular

  • Radio-opaqe bodies are seen within the lesion due to calcification process ( the calcifications increase with time )

  • Can be associated with unerupted teeth ( as the picture in the slides show)

  • The border is well defined as it’s a benign lesion

  • Differential diagnosis (odontogenic keratocyst , ameloblastoma , CEOT ,and other tumors ).

  • As the lesion progress , the calcifications increases and that gives the appearance of driven snow to the lesion ( old lesions appear radio-opaque not radiolucent as the new lesions ).

  • Associated with impacted teeth

  • So the presence of a radio-opacity will exclude the ameloblastoma and the keratocyst from the diagnosis

  • Histologically :

  • Unlike the ameloblastoma , this tumor is formed by sheets of large polyhedral epithelial Cells abundant eosinophilic cytoplasm.

  • Prominent intercellular bridges ( connections between the cells)

  • It contains features that could be misleading ( looks like a malignancy ) :

(Pleomorphism, multinucleation, hyperchromatism )of the nuclei

  • Inside the lesion we could find amorphous amyloid-like material deposited from epithelial cells , the presence of the amyloid can be confirmed by the histopathologist by using the" congo red stain" , this lesion is +ve for this stain so this test is a good diagnostic tool for this tumor .

  • The amayloid-like material can be calcified forming Spherical calcifications( by time the no. of calcifications inside the lesion increases )

Adenomatoid odontogenic tumour

Benign tumor

  • Clinically :

  • Start at the 2nd decade of life ( young patients mainly children )

  • On radiograph it may be misdiagnosed as a dentigerous cyst as in this age many teeth could still be impacted ( like the canines )

  • The difference between this tumour and the dentigerous cyst, is that its extended below the CEJ surrounding the crown and part of the root .

  • Its an intraosseous tumor , its rarely to be extraosseous

  • Radiograph:

Unilocular radiolucency containing a tooth

Some parts of the lesion could be calcified (Faint flecks of radio-opacities are found inside the lesion ) and this can help to differentiate it from the dentigerous cyst .

Differential diagnosis ; include the dentigerous cyst and keratocyst in addition to this tumor .

  • Prognosis :

Considered as a hamartoma so it’s a very benign lesion and has no recurrence possibility .

Histopathology :

  1. Surrounded by thick ,fibrous connective tissue wall

  2. Could be solid or cystic

  3. Islands/ Whorls surrounded by columnar epithelium called rosette , or ducts-like structures , the presence of ducts-like structures give this lesion its name (adeno)

  4. Homogenous eosinophilic material that could be calcified .

 Ameloblastic fibroma/fibrodentinoma/fibro-odontoma:

  • Contains both epithelial (ameloblastic) + mesenchymal (fibroma) tissues

  • Both components are neoplastic.

  • We have to differentiate between this tumor and the ameloblastoma !

  • Young patients

  • Slowly growing , painless mass

  • Mainly found in the mandible ( in the molars area )

Radiograph :

  • uni/multilocular radiolucency

  • associated with unerupted teeth so the differential diagnosis should include the keratocyst and the dentigerous cyst

note : we should always send a biopsy to the lab in these cases even if it looks as a benign lesion!

Histology :

  • its not a cystic lesion ( solid tissue )

  • Thin strands & cords of odontogenic epithelium

  • loose cellular fibromyxoid connective tissue ( looks like the dental papilla or the immature pulp tissue )

  • The stellate reticulum is less abundant unlike the ameloblastoma( which has stellate reticulum in the center and its epithelium is surrounded by fibrous tissue) where as in this lesion the epithelium is surrounded by cellular tissue.

  • Peripheral layer of cuboidal or columnar Cells enclosing Stellate Reticulum which is like what's found in the ameloblastoma

  • This tumor is different than the ameloblasoma in ( the prognosis , the surrounding tissue , the abundance of stellate reticulum )

  • As Ameloblastic fibroma contains dental pulp like structures + ameloblasts , formation of dentin like material could happen so its then called Ameloblastic Fibrodentinoma.

  • Sometimes , the process continues to form enamel , dentin and cementum so odontome complex forms , so its called ameloblastic fibro-odontoma

  • Prognosis : all types of this tumor are not aggressive , the local recurrence rate is low , and it's not an invasive tumor.


  • Can be compared with the previously mentioned ameloblastic fibro-odontoma .

  • This tumor is basically like an ameloblastoma which contain an odontoma

  • Its behavior is like the ameloblastoma (invasive and has high local recurrence rate ) so its more dangerous than the ameloblastic fibro-odontoma .

Calcifying cystic odontogenic tumour/cyst

The Solid form of it: Dentinogenic Ghost cell tumour

Clinically :

  • Usually the patients are < 40 years old

  • Occur in the anterior region

  • Slowly enlarging painless swelling

  • 25% extraosseous

Prognosis :

The soild form is more aggressive than the cystic form .

Radiograph :

  • Well defined uni/multilocular radiolucency containing radiopaque flecks

  • May be associated with unerupted teeth

So the differential diagnosis of tumors that contain radio-opacity and radiolucency include many tumors that were mentioned previously as well as many cystic lesions

The radiolucent margin around the lesion(fibrous connective tissue around it ) indicate that the lesion is benign .

So the radiograph is a good diagnostic tool to determine if the lesion is benign or malignant depending on the margins , whether it was well or poor defined .

Histopathology :

( this lesion is easy to be diagnosed depending on the histopathological features of it)

  • Cystic cavity that’s lined by basal ameloblast-like Cells & Stellate Reticulum

Unlike the unicystic ameloblastoma ,this lesion contain keratin-like deposits inside ghost cells

ghost cells : large epithelial cells that contain keratin

  • Dentine or odontome could be formed inside this lesion .

*note that the odontome could be associated with many odontogenic tumors *

Prognosis :

  • The soild form is more aggressive than the cystic form

Odontogenic fibroma & myxoma

  • This tumor is Mesenchymal in origin (Periodontal Ligament, Dental Follicle , Dental Papilla ) and its usually associated with a tooth or replacing a missing tooth.

  • The myxoma is infiltrative and has higher recurrence rate than the fibroma

  • We studied the fibroma in the CT ( the fibroepithelial polyp ) before, but here the fibroma is present within the bone ( Odontogenic fibroma ) or a myxoid tissue ( Odontogenic myxoma )

  • Odontogenic fibroma :


  • Slowly enlarging, painless benign tumor

  • Apper mainly in the Mandible and could be present in the gingiva rarely (Extraosseous)

Radiograph :

Well defined radiolucency , uni/multilocular

Histopathology :

  • Fibrous connective tissue (collagen & spindle-shaped fibroblasts)

  • Strands of odontogenic epithelium ( like rest cells of malassez ) could be found inside the CT

  • Calcifications could be found also

The presence of the odontogenic epithelium and the calcifications indicate that the lesion is peripheral odontogenic fibroma rather than fibrous epulis

  • Odontogenic myxoma:


  • More common compared with fibroma

  • Could be present either in Mandible or Maxilla

  • Slowly enlarging, painless (but the growth rate is higher than the fibroma )

  • Tooth displacement could happen

Radiograph :

  • Well defined , “soap bubble” appearance , multilocular radiolucency

  • Could cause resorption for the adjacent root ( tennis racket appearance )

Histologically :

  • Mucoid material surrounded by thin follicle fiber so its easy to be ruptured , so it can't be removed by inoculation , safety margins should be taken to ensure the complete removal of this tumor

  • angular cells with long anastomosing processes

  • no capsule present so this lesion is infiltrative inside the bone

mixed tumours of both fibroma and myxoma can be found and its named accourding to the dominant tissue as Fibromyxoma or myxofibroma

prognosis :

the presence of the myxoid tissue makes the prognosis worse than the fibroma as it has high recurrence rate ( 25% )

Benign Cementoblastoma

Only true neoplasm of cementum

• Clinically:

  • Young patients < 25, occurs in males more than females

  • Radio-opaque mass attached to the root , usually it occurs in the lower 1st molar & premolar

  • Slowly enlarging

  • Sometimes gives rise to pain and swelling

  • The Tooth is vital

  • ( if we see radio-opacity around non vital tooth osteosclerosis is the main diagnosis)

Treatment : surgical extraction and removing of the tooth(using a flap ) , simple extraction could cause fracture of the tooth or incomplete removal of the tumor .

  • Radiogragh :

  • Well defined radio-opaque mass in the late stage , but in the first stages it could appear as radiolucent mass . ( with time the radio-opacity increases )

  • Thin radiolucent margin surrounding the lesion ( benign )

  • Attached to the roots of a tooth ( continous with the periodontal ligament )

  • Resorption of related roots could happen

  • Histopathology :

  • Capsule ( fibrous connective tissue )

  • Mass of calcified material ( Cementum with many reversal lines)

  • Spaces that represent Peripheral zone of un-mineralized tissue containing cementoblasts

Now we'll take about the Malignant odontogenic tumours :

Malignant ameloblastoma:

• Typical histology of benign ameloblastoma but it undergone aspiration to the lung , it occur mainly with the lesios than was removed surgically more than one time

• Pulmonary ameloblastoma with the same histopathological features of the ameloblastoma in the mandible

• its an aspiration process not true metastasis which occur through the blood/lymph.

Ameloblastic Carcinoma:

• Ameloblastoma that contain follicles , surrounded by columnar cells , has stellate cells at the center but contains features of malignancy :

Hyperchromatism , polymorphism , high mitotic activity , invasion to the surrounding tissues .

Could spread to the lymph nodes ,

Primary intraosseous squamous cell Carcinoma

Originated from the odontogenic epithelium of the mucosa

Signs of malignancy are present within the lesion.

Clear Cell Odontogenic Carcinoma:

Rare tumor

Malignant tumor that infiltrate to the lymph nodes

Histopathology : large cells with clear cytoplasm that looks like the histopathological image of renal cell carcinoma

the patient should be examined for assurance that he doesn’t have renal cell carcinoma

Malignant change in odontogenic cysts:

• Clinically & Radiographically a Cyst exist

Histopathology : part of the cyst contains malignant features


_ Carcinoma change in a cyst

_ Cystic degeneration in a Carcinoma

_ Carcinoma invading the cyst

Odontogenic Sarcomas:

• E.g: Ameloblastic Fibrosarcoma

• Fibrosarcoma tissue and Non-neoplastic odontogenic epithelium

• ± dental hard tissue

Tumours of debatable origin:

Congenital gingival granular cell tumour (Congenital epulis):

Grandular cell tumour could be present in the tongue ( its named so as the histopathological features:

consists of large, closely packed granular cells covered by a flattened layer

of squamous epithelium

  • the surface of the tongue show hyperplasia so it could be misdiagnosed as SCC

Origin : unknown

Clinically: same as the grandular cell tumor in the tongue but it appear in a Newborn's gingiva

Anterior maxilla

Mainly female newborn

Pedunculated swelling from crest of alveolar ridge

Up to several cms in size


Looks like the grandular cell tumor but it has Atrophy of overlying epithelium rather than hyperplasia

Diagnosis : S100 –ve unlike the GCT which is S100 +ve

Treatment : local excision

Melanotic neuroectodermal tumour of infancy

Origin: neural crest


< 6 months newborn

brown or black pigmented swelling come from inside the maxilla0

mainly occur in Anterior Maxilla but can occur in Extra-oral sites : (brain , skull , testis )

Radiogragh: radiolucent area with tooth buds displacement


_ Two cell types ( the first type looks like the melanocyte and the second type looks like lymphocyte ) with dense Fibrous CT stroma

The presence of the melanocyte like cells give the lesion its name and it helps in the diagnosis


Hadeel Aljarhi

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