AMELOBLASTOMA

SUBMITTED BYMANJARI RESHIKESHIV BDS PART IIDEPARTMENT OF ORAL AND MAXILLOFACIAL SURGERY

TUMOUR- DEFINITION A tumour or neoplasm is defined as an

abnormal mass of tissue , the growth of which is uncontrolled & uncoordinated with that of normal tissue & persist in the same excessive manner even after the cessation of stimulus that evoked the change.- R.A. WILLIS

CLASSIFICATIONBased on origin• Odontogenic• Non Odontogenic

Based on its nature • Benign• Malignant

ODONTOGENIC TUMORS A. Benign

1. Odontogenic epithelium without odontogenic mesenchyme1. Ameloblastoma2. Squamous odontogenic tumor3. Calcifying epithelial odontogenic tumor4. Adenomatoid Odontogenic tumor

2. Odontogenic epithelium with odontogenic ectomesenchyme with or without hard tissue formation

1. Ameloblastic fibroma2. Ameloblastic fibro-dentinoma3. Ameloblastic fibro odontoma4. Odontoameloblastoma5. Calcifying odontogenic cyst6. Complex odontoma7. Compound odontoma

3.Odontogenic ectomesenchyme with or without included odontogenic epithelium1. Odontogenic Fibroma2. Myxoma3. Cementoblastoma

B. Malignant1. Odontogenic carcinoma

1. Malignant ameloblastoma2. Primary intra-osseous carcinoma3.Clear cell odontogenic carcinoma4.Ghost cell odontogenic carcinoma

2.Odontogenic Sarcomas Amelobastic Fibrosarcoma Amelobastic fibro-dentinosarcoma Ameloblastic fibro-odontosarcoma

AMELOBLASTOMA

“Usually unicentric,nonfunctional,intermittent in growth ,anatomically benign and clinically persistent” - Robinson

• True neoplasm of enamel organ type tissue

• Second most common odontogenic neoplasm

Originated from early english word ‘amel’ meaning ‘enamel’ and greek word ‘blastos’ meaning ‘germ’

It was recognised by Cusack in 1827

Named as adamantinoma by Louis Charles Malassez because of its histological similarity with adamantinoma of long bones

Coined as ameloblastoma by Churchill and Ivey in 1934

First detailed description given by falkson in 1879

CLASSIFICATIONClinical classification Central (Intraosseous)1. Conventional/ Multicystic/Solid (most common)2. Unicystic3. Peripheral (extraosseous)4. Pituitary ameloblastoma5. Malignant ameloblastoma

Based on histological type3. Follicular ameloblastoma4. Plexiform ameloblastoma5. Acanthomatous ameloblastoma6. Granular cell ameloblastoma7. Basal cell type of ameloblastoma8. Desmoplastic ameloblastoma

ETIOLOGYTraumatic episodes: Extraction, cystectomy, fracturesInfectionsDietary deficiency: vitamin D deficiency,Lack of protein intake Virus infection

Ameloblastoma is believed to be derived froma) Cell rest of enamel organ, either remnants

of dental lamina or Hertwig’s sheath, the epithelial rest of Malassez.

b) Epithelium of odontogenic cysts, particularly the Dentigerous cyst & odontomas.

c) Disturbance to developing enamel organ.d) Basal cells of the surface epithelium of the

jaws.e) Heteropic epithelium in other parts of body

especially the pituitary gland.

PATHOGENESIS

Age: 20-50 years Sex: no significant sex

predilectionRace: more common in

blacks than in white race.Site: mandible >

maxilla(more than 80% mandible)

with in mandible molar ramus area is affected three times more commonly than premolars & anteriors.

CLINICAL FEATURES

RELATIVE DISTRIBUTION OF AMELOBLASTOMA

SIGNS AND SYMPTOMS• it starts as a slow growing , painless, hard,

non tender, ovoid swelling which often enlarges in size as it causes little discomfort in early stage.

• Facial assymetry• Mobilty of teeth and exfoliation• Ill fitting dentures• Pain or paresthesia if impinges on nerve• Inability to occlude• Ulcerations

In the absence of treatment, • it may be extremely

disfiguring ,fungating and ulcerative like carcinoma

• Keeps on enlarging and cause “egg shell crackling’’& fluctuation

• Palpation elicit hard sensation or crepitus.

• Not encapsulated

• Invades surrounding tissues

• Bone destruction is a common finding by invasion to bone marrow

• Root resorption is caused

SIZE: small as 1cm to large as 16 cmSPREAD: local invasion

Causes expansion of bone than destruction. • infiltrates cancellous bone but never cortical

bone

MURAL AMELOBLASTOMA: ameloblastoma from dentigerous cyst

• MAXILLARY AMELOBLASTOMA: • common in tuberosity. more dangerous as1. It may cause nasal obsturction2. proptosis of eye3. Damage vital structures4. Involve cranial base5. Cause gross facial distortion

VICKER’S AND GORLIN’S CRITERIA

1.Tall columnar cell2.Hyperchromatic nucleus3.Palisaded nuclei4.Reverse polarity of nuclei5.Subnuclear vacuole formation

HISTOLOGY

HISTOLOGIC FEATURES

6 HISTOLOGIC SUBTYPESFollicular ameloblastomaPlexiform ameloblastomaAcanthomatous ameloblastoma

Granular ameloblastomaBasal cell type of ameloblastoma

Desmoplastic ameloblastoma

FOLLICULAR AMELOBLASTOMA*Small discrete islands of

tumour cells.*Peripheral layer of cuboidal or columnar cells.

*Nuclei well polarized.*Resembles ameloblast.*Cyst formation is relatively common.

*Stellate reticulum like cells prominent enclosed by columnar or cuboidal cells

Plexiform ameloblastoma Ameloblast like cells

arranged in irregular masses.

Networks of interconnecting strands of cells.

Each strands bounded by layer of columnar cells.

In b/w these present stellate reticulum like tissues less prominent compared to follicular ameloblastoma.

Areas of cystic degeneration is common.

ACANTHOMATOUS AMELOBLASTOMA• Cells occupying the position

of stellate reticulum undergo squamous metaplasia

• Sometimes with keratin formation in the central portion of tumor islands

• Usually occurs in follicular type

• Sometimes keratin pearls may be observed

GRANULAR CELL AMELOBLASTOMA• Marked transformation of cytoplasm,usually of

stellate reticulum like cells become coarse,granular,eosinophilic appearance

• Include peripheral columnar or cuboidal cells• Hyperchromatism• Reverse polarity

BASAL CELL AMELOBLASTOMA• Bear resemblance to basal

cell carcinoma of skin• Rarest histologic subtype• Hyperchromatic ,less

columnar,arranged in sheets without peripheral palisading

DESMOPLASTIC AMELOBLASTOMA• Found in a dense collagen

stroma that is hypocellular and hyalinized

• Grow in thin strands and cords of epithelium

• Epithelial proliferation seems to be compressed and fragmented by hyalinised stroma

UNICYSTIC AMELOBLASTOMA single cystic cavity showing ameloblastomatous differentiation

Age: The patients are younger than those with the solid/multicystic form ie around 20 yrs

Sex Predilection: equalLocation: 90 % occur in the mandible usually in the posterior region

Typically surrounds the crown of unerupted mandibular third molar and resembles dentigerous cyst

HISTOLOGYACKERMANN CLASSIFICATION

Luminal type: the tumor is confined to the luminal surface of the cyst by fibrous connective tissue partially or totally

Intraluminal: the tumor nodules projects from the cystic lining

Mural: the tumor infiltrates the fibrous cystic wall.(high recurrence rate)

RADIOGRAPHIC FEATURES• Presents a unilocular or

multilocular radiolucency in diff forms and shapes

• 50% multilocular,2% peripheral and 6% unicystic lesions

• Multilocular radiolucency with compartmentalised appearance due to bony septa (HONEY COMB or SOAP BUBBLE APPEARANCE)

• Root resorption and tooth displacement

Soap bubble appearence

Honey comb appearence

• Small / large unilocular or multilocular lesion may show unerupted tooth

• Buccolingual cortical expansion( hollowing out)

C- soap bubbleD- honey comb

UNICYSTIC TYPEWell defined radiolucent lesion with minimal peripheral sclerotic border

Mimics dentigerous cystAssociated with impacted 3rd molarIn adv stage thinning of cortical bone seen

• Maxillary lesions involve maxillary sinus and make it more opacified appearance

• CT SCAN and 3d reconstructions

PERIPHERAL AMELOBLASTOMARare typeDevelops in softtissue of gingiva and mucosa

Non invasiveClinical features*Younger individuals*Mandible>maxilla*In premolar region*Apperas as a nodule on the gingiva/ mucosa*Size 3mm-2cm

Pituitary ameloblastomaPITUITARY AMELOBLASTOMA• Craniopharyngioma/Rathke’s pouch tumor.• Neoplasm involving CNS.• Grows as a pseudo encapsulated mass in the

suprasellar area and destroys pituitary gland.• Clinical features-• endocrine disturbances,drowsiness& even

toxic symptoms.

MALIGNANT AMELOBLASTOMA

• Malignant transformation of ameloblastoma• Rare lesion• Almost exclusively in mandible• Mean age: 28-32 yrs• Common sites for metastasis;

Lungs,spleen,kidney,ileum

Investigations

• RADIOGRAPHS• Biopsy• CT• MRI• ultrasound

TREATMENT

• Treatment options include:a) Radical & conservative surgical excision.b) En bloc resectionc) Segmental resectiond) Curettagee) Chemical & electrocauteryf) chemotherapyg) radiation.

SIMPLE EXCISION/ENUCLEATIONIn case of peripheral ameloblastoma,simple excision of the lesion is performed

ENUCLEATION&CURETTAGE• In peripheral ameloblastoma, simple excision is

performed• Means removal of the tumor by scraping it from

the surrounding normal tissue.• Curettage given a cure rate of only 10%• 60-90% of recurrence rateComplications of curettage• Seeding into lungs• Malignant transformation• Failure of curettage is probably related to the

fact that the nest of tumor cells extend beyond clinical & radiographic margins of the lesion.

• Therefore impossible to eradicate the lesion by scraping procedure.

ENBLOC RESECTION• Means removal of tumor with a rim of uninvolved

bone but maintaining the continuity of jaw.• Frequently used therapeutic measure.• Kramer 1963 reported that although there is a

diffuse invasion of cancellous spaces of the bone marrow by finger like projections it does not invade haversian system of compact bone.

• A 1-2 cm margin beyond the radiographic limit is considered the minimum acceptable margin for resection.

• Least no of recurrences reported

SEGMENTAL RESECTION

• Means removal of segment of the maxilla / mandible up to & including hemi section or more.

• Includes hemimaxillectomy & hemimandibulectomy.

• Most Commonly used treatment.• Least chance of recurrence.• It is noted that the lesion most likely

to recur after segmental resection are those over 5cm.

Chemotherapy•May be sensitive to platinum agents•May have role in improvement in non

surgical patients•Eg;

cyclophosphamide,cisplatin,vinblastine,methotrexate etc

Desiccation / electro coagulation of the lesion including various amount of surrounding normal tissues.

Not been commonly used as primary mode of therapy.

Much more effective therapy than curettage.

50% recurrence rate.Because of poor results –not been used

as a sole method of treatment.

electrocautery

Radiation therapy

• Ameloblastoma is generally radioresistant• Post operatively in pts with gross/microscopic

residual disease• Recurrent disease• Pts who are poor candidates of surgery

rehabilitation with obturator in maxilla

POST OPERATIVE MANAGEMENT

Reconstruction with graft

RECONSTRUCTION WITH TITANIUM PLATES AND SCREWS

Simple curettage- 90% recurrence rate.

Ameloblastoma of maxilla – more aggressive – poor prognosis.

PROGNOSIS

Ameloblastic fibromaOdontogenic myxomaCentral giant cell granulomaDentigerous cystOKC

DIFFERENTIAL DIAGNOSIS

Daniel.M.Laskin – oral & maxillofacial surgery-

volume 2

Shafer’s textbook of oral pathology-

7th edition

REFERENCES

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