Odontogenic Tumours

Important causes of swelling of the jaws: 1) Cysts especially odontogenic ones.

2) Odontogenic tumours ( most common neoplasms).

3) Giant cell lesions.

4) Fibro-osseous lesions.

5) Primary ( non-odontogenic ) neoplasms of bone.

6) Metastatic neoplasms.

7) Chronic osteomyelitis.

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Classification of odontogenic tumours according to the behaviour of the lesions

(I) Benign

Epithelial Mesenchymal Mixed 1- Ameloblastoma 1- Od. Fibroma 1- Ameloblastoma Fibroma

2- Adenomatoid 2- Od. Myxoma 2- Odontomas

odontogenic 3- Cementoblastoma

tumour

3- Calcifying epithelium

Od. Tumour

4- Squamous odontogenic

tumour

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(II) Malignant

Epithelium Mesenchymal Mixed

1- Malignant Ab - Odontogenic -Amelofibrosarcoma

2- Ab. Carcinoma Fibrosarcoma

3- Odontogenic

Carcinoma

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I - Benign Epithelial Odontogenic tumours

1)Ameloblastoma : - It is the most common neoplasm of the jaws.

Clinical features : Age : Between 3rd to 5th decades.

Sex: No sex predilection

Site : Mandible more than maxilla 80% of cases were in mandible . In the mandible 70% of cases were in molar ramous region.

Characters :

- Asymptomatic

- Slowly growing

- Discovered by X – ray

Radiographic Appearances :

1) Multilocular radiolucent area.( Honey comb pattern) & expanded lingually

2) Unilocular radiolucent area usually associated with impacted tooth ( as in dentigerous cyst).

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Ameloblastoma. Typical presentation. There is a rounded, bonyswelling of the posterior alveolar bone, body and angle of the mandible.There is no ulceration, a feature only seen in very large tumours whichhave perforated the cortex.

Ameloblastoma. The typical radiological appearance ofameloblastoma is a multilocular cyst or multiple cyst cavities of differentsizes, as shown here.121Odontogenic tumours andtumour-like lesions of thejaws5

Macroscopic appearances :

- Solid or cystic or both together.

- Traversed by bony ridges.

Microscopic appearances:

-Different histological patterns are seen under microscope.

-The epithelium forming this neoplasm resembles that epithelium which forms the enamel organ.

- The fibrous stroma surrounding this epithelium vary in both quantity & cellularity ( not neoplastic one).

- In most cases the stroma is collagenous with few cells while in other cases , the stroma may be abundantly cellular .

Two main histological patterns are commonly seen in ameloblastoma.

1- Follicular

2- Plexiform.

Follicular Ameloblastoma: In this patterns , the odontogenic epithelium takes the form of discrete islands separated from each other by variable C.T. stoma ( non - neoplastic C.T.).

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Ameloblastoma. This ameloblastoma forms a monolocular radiolucency enveloping the crown of an unerupted tooth. The radiological appearance mimics a dendgerous cyst, reinforcing the maxim that ameloblastoma should be considered in the differential diagnosis of every radiolucency at the angle of the mandible.

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Ameloblastoma. At high power in this follicular ameloblastomathe palisaded, elongated peripheral cells with reversed polarity are seen tobe very similar in appearance to ameloblasts.

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Variants :

1-Solid form : Typical follicle consists of :

i – Peripheral layer of cuboidal or columnar cells resembling the pre-ameloblasts . This layer is called ( ameloblastic like cells). The nucleus of that cell is deeply stained & at the opposite pole to the basement membrane.

ii- Central mass of polyhedral cells which are loosely anastomosing & resembling the stellate reticulum cells. These cells are called ( stellate reticulum like cells).

2- Cystic formation: Common : cystic breakdown & epithelium is usual this degeneration occurs in stellate – reticulum like cells.

i) Microcystic : This represent the starting of the process of degeneration .Small microcysts appear in central mass of the follicle. The peripheral layer of ameloblast – like cells become low cuboidal due to slight pressure of minute cystic fluid.

ii) Macrocystic : Microcysts will fuse to form a larger cyst filling the whole center of the follicle . The peripheral cells will become flattened & the lesion may be mistaken for a simple cyst. However many other areas will show the typical follicular form beside the cystic form.

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3) Acanthomatous form :

- Areas of squamous metaplasia may be found ( so high recurrency & may turn malignant).

- The central cells become squamous , compact to each other.

- The tendency of squamous metaplasia appear to be increased by :

* Previous operation

* Radiation therapy

- In many areas of acanthomatous ameloblastoma , keratin may be formed & may be so prominent that the neoplasm is referred to as ( kerato ameloblastoma).

4) Granular ameloblastoma :

- In rare cases , the follicles show their central cells undergo a granular change. Part or all the tumour may show this variation.

- The central cells are larger than normal , cuboidal , rounded or columnar in shape with their nuclei pushed against the cell wall & their cytoplasm is filled by coarse eosinophilic granules.

- These granules are best demonstrated by E/M or histochemically & are said to be lysosome – like particles called phago - lysosomes.

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Ameloblastoma. Islands of ameloblastoma penetrating surrounding bone at the periphery of the lesion. Such bony infiltration demands that ameloblastoma is excised with a margin rather than curetted.

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5) Basal cell ameloblastoma :

The peripheral cells become cuboidal rather than columnar & central cells become more compact. It cab be mistaken from basal cell carcinoma .

6) Hyalinized C.T. stroma :

The stroma around epithelial masses undergo hyalinization to involve a zone of about ( 30 microns) immediately adjacent to epithelial follicle. This zone is due hyaline degeneration of collagen fibers. This zone does not calcify ( i.e. remain eosinophilic. This zone is not diagnostic for ameloblastoma.

7) Desmoplastic ameloblastoma : ( low recurrency)

The C.T. stroma is usually consisted of a cellular loose C.T. but in some cases it becomes more collagenous with small follicles of epithelium.

Plexiform Ameloblastoma :

- In this variant , the tumour epithelium is arranged in the form of irregular intercommunicating anastomosing strands but not in the form of discrete islands as in follicular variant.

I) The arrangement of cells of these strands is the same as that of follicular – AB i.e. they are bounded by a layer of columnar or

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Ameloblastoma. Granular cell change in an ameloblastoma.Ameloblast and stellate reticulum-like cells have undergone degenerative change to form large pink granular cells. In some tumours this change is extensive and the term 'granular cell ameloblastoma' is applied.

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Or cuboidal cells ( ameloblastic like cells) Surrounding another layer of loosely intercommunicating cells ( stellate reticulum like cells) but less abundant ( this form called solid plexiform ameloblastoma).

II) Cystic plexiform AB :

- In some cases , cystic degeneration of C.T. stroma occurs leading to stromal cysts.

- In some cases , following stroma degeneration many spaces are found filled with blood & lined by epithelial strands. These cases have been called Hemangio - AB.

- However , this term is not correct since no neoplastic change could be seen in vascular endothelium , but however it represents vasodilataion of stromal B.Vs that have lost their support by stromal degeneration.

- These various histological patterns seen in ameloblastoma have given rise to the different nomenclatures. However , these variants are not accompanied by variation in clinical picture or behaviors as well as treatment , because in one patient many histological variants could be seen under microscope.

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Plexiform unicystic ameloblastoma: It is a recent distinct entity of AB

Histologically :

- Cystic cavity lined by tumour cells which are flattened ( non descript epithelial cells & no ameloblast like cells).

- Unicystic plexiform ameloblastoma differs from the solid types in the following : Low recurrence rate , so , treated without safety margin ( just enucleation).

Histogenesis of ameloblastoma :

Several origins have been proposed as the origin of ameloblastoma .

1) Basal layer of oral epithelium : Due to :

A- Since few cases arises in soft tissue basal layer is suggested to be the origin.

B- Basal cell ameloblastoma resemble basal cell carcinoma.

2) Dental lamina or it is remnants : because

A- few cases a rise in soft tissue ( rests of Serres are present in gingiva).

B- Different in histological patterns suggest the different pontencially of dental lamina . Arise at any age.

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3) Enamel organ or it is remnants : because

A- Some cases arise with impacted tooth.

B- Follicular Ab resemble enamel organ.

4) Epithelial lining of a follicular cyst : due to

A- Ab are common arised in the areas of dentigerous cyst.

B- May be mistaken radiographically as a dentigerous cyst.

C- Ab may arise with impacted tooth.

Behaviour & local spread of AB:

1) Ab tend to spread into cancellous ( spongy) space without resorption of the compact bone.

2) Therefore the tumour tissue extend into areas of bone that appear in X-ray normal .

3) This invasive character of AB & absence of capsule around the tumour would suggest the local invasive nature of this neoplasm.

4) Since Ab does not tend to invade compact bone , the inferior border of the mandible represents the actual limit of that neoplasm.

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Ameloblastoma. Plexiform ameloblastoma composed ofinterconnecting strands of epithelium surrounding islands of connective tissue. Several of the stromal islands have degenerated to form small cystic cavities.

Ameloblastoma. Islands of follicular ameloblastoma comprisingstellate reticulum and a peripheral layer of elongated ameloblast-like cells.

Ameloblastoma, plexiform type. There are thin, interlacingstrands of epithelium but typical ameloblasts are not seen.

Squamous metaplasia in an ameloblastoma. Stellate reticulum- like cells have undergone squamous metaplasia to form keratin.

Ameloblastoma. Soft tissue spread after repeated inadequate excisions.

Ameloblastic carcinoma. Very rarely a malignant variant of the ameloblastoma is encountered. Histologically they may be indistinguishable from other carcinomas, but in some cases, as here, a peripheral layer of palisaded ameloblast-like cells remains, indicating thetumour's nature.

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Diagnosis of Ab :

1- biopsy for histological examination.

2- X- Ray .

3- Magnetic resonance ( solid or cystic types).

Treatment :

1- Surgical removal with safety margins.

2- Large tumours may require bony resection or even the whole jaw.

3- Ab id radioresistent tumour so it is not treated by radiotherapy.

Prognosis :

1- Solid & multicystic have a higher tendency to recur when treated conservatively ( i.e. without safety margin )

2- Maxillary Ab when allowed to reach a large size may give rise to serious complication .

3- Adequate treatment gives good prognosis.

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Malignant epithelial odontogenic tumours :

1) Malignant Ab 2) Ameloblastic Ca. 3) primary intra-osseous Ca.

Malignant AbAmeloblastic Ca1ry intra-osseous Ca.

Defintion Rare jaw Tu. That gives rise to distant M. with

histological picture of AB . It gives metastasis to the

pulmonary area , may be due to aspiration

implantation.

A variant of malig. AB but with metastatic Tus. Showing sq. C.Ca AB

turn into Ca by Sq. metaplasia , it spreads

to L.N.

It is a Sq.C.Ca. arising within the jaw having no initial connection

with oral epithelium & arises from odontogenic

epithelium undergiong squamous metaplasia

Histological picture

Both 1ry & 2ry Tus. show picture of AB with definite

histologic & cytologic criteria of malignancy

1ry Tu. Show typical AB as well as picture of

Sq.C.Ca. 2ry Tus. Show typical Sq.C.Ca. ( due to Sq. metaplasia

of odontogenic epithelium)

Both 1ry & 2ry Tus. Show typical Sq.C.CA. the 1ry Tu. May show odontogenic patter of

distribution i.e. plexiform pattern for

example with palisaded peripheral

cells.

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2- Adenomatoid Odontogenic Tumour It is benign epithelial odontogenic Tu. Characterized by duct like structure &

variable degrees of inductive change . It is probably a hamartoma.

Clinically : Age 2nd decade of life ( young adult).

Sex : Female more than male .

Site : Maxilla > mandible 2: 1 , most common in canine region.

Characters :

1- Slowly growing .

2- painless discovered by chance on X-ray.

3- cause jaw expansion especially of upper canine region .

4- Usually related to unerupted tooth ( may resemble dentigerous cyst both clinically & radiographically ).

Radiographic picture :

- Well defined radiolucent area related to unerupted tooth.

- Inside this radiolucency , scattered radiopaque areas may be seen.

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Macroscopic picture :

-Size : few centimeters, capsulated.

- Cur surface : is greyish white in colour with dark areas of hemorrhage.

- It may show one or more cystic spaces .

- A tooth may be embedded in it .

Histopathology ( microscopic picture) : This tumour is capsulated.

1- The Tu. Is composed of sheets of small or spindle shaped epithelial cells with clear cytoplasm & oval nuclei.

2- These sheets or masses are arranged in whorly patterns.

3- Some of these cells will differentiate into tall columnar cells resembling ameloblasts & arranged in different patterns as follows :

I) Tubular structure : Two rows of cells with eosinophilic homogenous material in between the two rows.

II) Convoluted bands : Two rows of cells with eosinophilic material in between the two rows & with a shape of convoluted tubules.

III) Duct – like structures : Some of tubular structures may expand ( open) to include a central space surrounded by single layer of flat columnar cells.

-The nuclei of these radially arranged tall columnar cells are situated at

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-The nuclei of these radially arranged tall columnar cells are situated at The basal of the cell.

- The central space contains a homogenous eosinophilic material forming a thin layer in contact with the free end of the cells.

N.B. : This eosinophilic material is thought to be a basement membrane like material since it is PAS positive.

The tumour contains very small amount of C.T. stroma which may undergo degeneration to give a cribriform pattern under microscope.

- Small foci of calcification or hyaline material may be present which was described as dysplastic abnormally formed dentin.

Histogenesis of adenomatoid odontogenic tumour:

Enamel organ or it is remnants.

Treatment : This tumor is capsulated , so it is treated with simple enucleation.

Prognosis : Good prognosis since the tumour is benign with no rate of recurrence as it is capsulated.

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Adenomatoid odontogenic tumour. At higher power the duct- like spaces which give the tumour its name are seen.

Adenomatoid odontogenic tumour. Low magnification shows duct-like microcysts and convoluted structures. The stroma is scanty.

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Calcifying Epithelial Odontogenic Tumour

Pindborg Tumour It is a benign but locally invasive epithelial neoplasm characterized by

development of intra-epithelial amyloid like material which may become calcified & liberated into surrounding stroma. Relatively rare neoplasm as compared to AB , but it could be mistaken for a poorly differentiated carcinoma.

Clinical picture : Age : Average age is 40 years.

Sex : pindborg discovered that male & female occurance in equal incidence.

Site : Mandible > Maxilla 2: 1, In mandible , the most common site is molar premolar region. Molar 3 : 1 Premolar

Half the cases are associated with the crown of unerupted tooth.

Characters : 1- Slowly growing . 2- Symptomless.

3- Hard ( due to calcification).

4- Diffuse or well – defined swelling.

5- Usually a missing tooth is observed at site of the tumour.

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Radiographic picture :

- Irregular radiolucent area with radiopaque areas of variable size usually related to the crown of unerupted tooth.

- The peripheral zone of this lesion is radiolucent which may or may not be well demarcated from the normal bone.

- Usually radioopacities increase within the tumour as it matures.

Histopathology :

1- Tu. is made up of sheets of polyhedral epithelial cells with well defined borders & prominent inter cellular bridge & may show cellular pleomorphism.

2- Rounded eosinophilic homogenous masses are often present in the epithelial masses.

3- These masses are commonly calcify in concenteric way to form what is called ( Leisgang rings) .

4- Epithelial cells may degenerate to liberate the calcific basophilic rings into the surrounding stroma.

5- Fusion between calcific rings occur to form large irregular masses.

6- The eosinophilic pink material give the similar staining reaction of amyloid.

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Origin of this amyloid material may be due to :

I) Active secretion of these cells.

II) A product of polyhedral cells degeneration.

Histogenesis : Most probably from reduced enamel epithelium of impacted unerupted tooth.

Treatment As in AB. , curettage will result in recurrence ( not capsulated).

Prognosis : Complete resection of the Tu. – bearing area of the jaw will result in complete & permanent cure with good prognosis.

Causes of aggressiveness of this neoplasm:

1- Irregular growth of neoplasm towards the surrounding bone.

2- Lack of encapsulation ( the tumour is not capsulated).

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Calcifying epithelial odontogenic tumour (Pindborg tumour .The tumour is composed of strands and sheets of polyhedral epithelial cells lying in pale pink staining amyloid-like material. Some of this material has mineralised, stains a darker blue colour and gives rise to radiopacities within the lesion.

Calcifying epithelial odontogenic tumour. At higher power the epithelial cells are seen to have sharply defined cell membranes resembling squamous epithelium and pleomorphic hyperchromatic nuclei. The pale pink material is amyloid-like.

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Clear cell odontogenic carcinomas. This neglected tumour hasfungated through the cheek.

Clear cell odontogenic carcinoma. This rare epithelialodontogenic tumour is composed of pale-staining clear cells.

4- Squamous odontogenic tumour It is an intrabony ( central) benign but locally invasive neoplasm arising from

islands of well differentiated squamous epithelium present in fibrous stroma. This neoplasm was considered as a variant of simple AB.

Clinical picture: Few cases were discovered.

Age : common age 3rd decade. Sex : equal Site : Mandible = Maxilla

The tumour is multicenteric ( i.e. in many bones).

Characters :

1- Most cases follow a benign course i.e. slowly growing painless .

2- In other cases , the tumour may be :

- Rapidly growing .

- Cause bone destruction.

- cause surface ulceration.

Radiographic picture : Unilocular radiolucent area.

Histological picture :

1) Islands of well differentiated squamous epithelium pained in collagenous C.T. stroma ( resemble follicular AB)

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2) Epithelial islands , in contrast to simple AB , are surrounded by a layer of flat low cuboidal cells.

3) Epithelial islands may undergo calcification.

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Squamous odontogenic tumour. The lesion is composed of islands of squamous epithelium without peripheral palisaded cells.

Melanotic Neuroectodermal Tumour in infancy It is a rare neoplasm or hamartoma of unknown nature & is confined to

infants less than one year old.

Clinical features : Age : Infants less than on year ( 6months).

Sex: Female more than male.

Site : Maxilla > Mandible ( maxilla anterior region mostly).

Characters:

1) Pigmented or non-pigmented swelling of the gums.

2) May be central ( i.e. intrabony)

3) Initial rate of growth is rapid ( resemble malignancy) then , the rate

becomes slow after sometimes & then it may stop , when the tumour

reaches a certain site.

Radiographic picture :

- Peripheral lesion ( outside bone) is negative in X ray except when causing bone erosion.

- Central lesion is radiolucent area usually multilocular with displacement of neighbouring teeth.

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Histopathology : The lesion is not capsulated , two types of cells are found :

I) Epithelium like cells : Arranged in strands or sheets or duct like structure.

II) Lymphocyte – like cells :

- darkly stained.

- May be small cells with dense rounded nucleus or may be larger

with larger nucleus showing fine chromatin.

- Lymphocyte like cells may be found inside duct like structure of

epithelial like cell.

* Sometimes , other type of cells is also present we can find small collection of polyhedral or stellate cells filled with fine melanin granules.

* The lesion is not capsulated & the margins of the tumour is irregular giving invasive appearance of that lesion.

* These types of cells are found in well formed C.T. stroma which is sometimes fibrillated.

Histogenesis : 1) Pigmented lesions are derived from dentritic melanocytes of neural crest origin . These cells ( melanocytes) are included in dental lamina & enamel organs.

2) Epithelial like cells may be originate from paradental epith.

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Benign Epithelial Hard odontogenic tumours :

Enameloma ( enamel pearl) : This is a developmental malformation in which small

nodule of enamel develop on the radicular portion of a tooth usually upper molars at or near the root bifurcation.

Macroscopically : It is a small circumscribed nodule of normal enamel.

Histologically : it may be

1- Normal prismatic structure

2- Normal enamel with a core of dentin & pulp tissue

Histogenesis : It develops as a result of disturbed development of an area of epithelial root sheath of Hertwig differentiated into enamel organ lying down enamel

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Enamel pear -A small, spherically shaped enamel projection on a root surface is called an enamel pearl. It is usually seen on maxillary molars in the furcation area. This photograph shows the mesial view of a maxillary third molar.

Benign Mesenchymal odontogenic tumours

1- Odontogenic fibroma

2- Odontogenic myxoma

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Odontogenic fibromaOdontogenic myxoma

Definition Benign fibroblastic neoplasm with presence of epithelial rests ( odontogenic origin) .It is rare endosteal tumour

Benign , but locally invasive neoplasm consisted of stellate cells in mucoid stroma ( resemble developing dental papilla

Clinical picture Age : 1st two decades of life may be discovered later.Sex : equal Site : mandibular molars - premolar

Age : young adults Sex : equal Site : mandibular > Maxilla 60 : 40%

Clinical features1) Painless2) Slowly growing 3) Well circumscribed4) Cause slight jaw expansion5) Usually arise near root of tooth or in

place of missing tooth

1) Usually painless2) Rapidly growing due to

accumulation of mucoid material

3) Fusiform swelling 4) Cause jaw expansion 5) Usually covered by only

thin layer of bone6) Usually related to place of

missing tooth

X – ray Sharp defined radiolucent area in a tooth bearing region

Multilocular radiolucent area , soap – bubble radiolucency wit a crown of impacted tooth

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Histopathology 1) Primitive cellular C.T.2) Between fibroblasts

are found inactive islands of odontogenic epithelium

3) Collagen fibers are variable in amount but usually the lesion is cellular

4) Sometimes , islands of osteoid or cementoid tissues could be found

1) Primitive myxomatous tissue 2) Stellate or spindle shaped cells with long

anastomosing processes with basophilic cytoplasm3) These cells are found in mucoid matrix is faintly

basophilic4) In this matrix , two types of fibers are present : A-

collagen B- Reticulin5) Sometimes , the nuclei of stellate cells show: a-

Atypical shape b- Hyperchromatism6) In active islands of epithelial cells are usually

present 7) The tumour may contain moderate amount of

collagen fibers & the lesion is called fibromyxoma

HistogenesisThis lesion originates from : Fibroblastic tissue of tooth follicle or it is remnants in periodontal tissue . ( pressure of cementum like tissue support this origin)

This lesion derived from odontogenic mesenchyme of dental papilla because of it is resemblance to that site , this theory is supported by : 1) Presence of impacted or missing tooth 2) Absence of that tumour in other bones

TreatmentComplete removal by simple enucleation

Complete removal with safety margin ( as locally invasive)

PrognosisGoodGood , if the tumour is removed with safety margin 37

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Odontogenic myxoma of the mandible. An occlusal view showing the finely trabeculated, soap-bubble appearance and gross expansion of the mandible . Evidence of residual tumour was still present after 35 years in spite of vigorous treatment, both surgery and radiotherapy, in its earlier stages. 129

Odontogenic myxoma. High power view showing the typical appearance of sparse fibroblasts lying in a myxoid or ground substance rich matrix.

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Odontogenic fibroma. This rare mesenchymal odontogenic tumour consists of fibrous tissue containing rests and strands of odontogenic epithelium resembling those found in the periodontal ligament.

3) Cementoblastoma It is the only neoplasm of cementum . Ii is a benign one

Clinical features : Age : young adults Sex: Male more than female

Site : Mandibular first molar region

Characters : slowly growing , painless , vital tooth

X-ray :

- radiopaque mass with a radiolucent rim attached to the root apex

-resorption of the related roots is common - Vital tooth

Histopathology :

1- mass of cementum with many reversal lines

2- Cellular C.T. with cells resemble osteoblast & osteoclast

3- may be mistaken as osteosarcoma ( when it is very cellular )

4- Peripherally : a band zone of unmineralized tissue a surrounding C.T. capsule

Treatment : excision with tooth extraction with good prognosis

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Periapical radiograph showing the typical appearances of a cementoblastoma, a radiopaque mass with a radiolucent rim attached to the root apex.

At high power at the periphery of the lesion there are radiating seams of osteoid with a thick layer of atypicalcementoblasts on their surface.

A dense mass of interconnected trabeculae of osteoid is fused to the resorbed roots of the first permanent molar.

Malignant Mesenchymal Odontogenic tumours

Odontogenic Fibrosarcoma :

1-This is a rare neoplasm which result from malignant transformation of odontogenic fibroma.

2- Histologically : it resemble odontogenic immature C.T. fibroma but the cells show histological & cytological criteria of malignancy .

3- Rate of growth is variable

4- Treatment is by complete excision with safety margin

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Mixed odontogenic tumours Benign

1) Ameloblastic fibroma

It is a mixed odontogenic tumour composed of actively proliferating neoplastic odontogenic epithelium found in cellular actively proliferating neoplastic fibrous tissue similar to tooth follicle or dental papilla of the developing tooth.

Clinical features : Age : below 21 years Sex : M > F

Site : Mandibular premolar molar area

Characters : Rare , Painless , slowly growing , produce jaw expansion & does not invade the surrounding the surrounding bone

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X-ray : Well defined unilocular or multilocular radiolucent area sometimes with impacted tooth

Histopathology :

1) The epithelial element forms follicles similar to ameloblastoma i.e. peripheral layer of cuboidal or columnar cells & central mass of stellate cells.

2) The follicles of epithelium form several shapes : Compressed follicle , small nest & rossetts

3) The C.T. is much more cellular than C.T. ameloblastoma & the cells are fusiform or angular with primitive fibrous tissue resembles immature dentine papilla

4) Sometimes , a layer of juxta epithelial hyalinization is found around the epithelial islands

Treatment : excision with safety margin44

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Ameloblastic fibroma. The appearance is somewhat similar to that of ameloblastoma but the pattern of budding strands is distinctive and the connective tissue resembles the undifferentiated mesenchyme of the dental papilla.

Ameloblastic fibroma. At higher power the resemblance to dental papilla, ameloblasts and stellate reticulum is seen more clearly.

2- Ameloblastic fibro-odontome

- It is that tumour resemble ameloblastic fibroma but with inductive changes leading to formation of enamel & dentin

- It is difficult to differentiate that lesion from the early stage of composite odontome

X ray : Multilocular well defined radiolucent area with radiopaque masses

Histology :

1- Similar to odontogenic myxoma but with odontogenic epithelium showing active ectomesenchymal border ( the layer just around the epithelium is called cell rich zone)

2-Formation of enamel & dentine ( i.e. induction changes are found)

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Compound odontome Complex odontome

DefinitionDevelopmental malformation ( hamartoma) consisted of large number of denticles in which enamel , dentin , cementum are arranged in normal fashion

Developmental malformation ( hamartoma ) in which the enamel , dentine & cementum are arranged in habhazard fashion

Clinically Age : children & young adults Sex : F > MSite : mandibular molar area

Age : children & young adults Sex : F>MSite : Mandibular molar area

CharactersThe lesion is usually smallAsymptomatic

Causing expansionDiagnosed by routine X rayIt is associated with permanent dentition but may be associated with deciduous teeth.Multiple odontomes could be present

It is usually small Asymptomatic Causing jaw ion

Small lesion are diagnosed by X raySome cases develop in association with a place of missing tooth

Xray Radiopaque Numerous tooth like structures arranged in various fashions

Radiopaque area

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3 -Odontomes

Histopathology Early stage : Denticles are embedded in

fibrous C.T .Hard tissue start to form with development of tooth like

structures consisted of : Central core of pulpSurrounded by a layer of dentinCoronal part consisted of enamel ( empty space in decalcified section )

Radicular part covered by layer of cementum

Enamel , dentin & cementum forming irregular mass

Treatment Enucleation Removal with conservative surgery

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Compound odontoma. A denticle of dentine surrounded by enamel matrix is lying within more irregular calcified tissues.

Complex odontoma. In this radiograph the odontoma overlies the crown of a buried molar and shows the typical dense amorphous area of radiopacity.

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Compound odontoma. Sections from various areas of the odontoma, show denticles of dentine and enamel cut in various planes, and more irregular calcified tissues, within a connective tissue capsule. 135

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Complex odontoma. A disorganised mass of dentine, enameland cementum penetrated by fine divisions of pulp.

Malignant mixed odontogenic tumours

- It is a malignant variant of ameloblastic fibroma ( The

ectomesenchymal part show malignant criteria)

- It is more aggressive than it is benign

- More invasive with distant metastasis

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