Ameloblastoma / oral surgery courses

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AMELOBLASTOMAAMELOBLASTOMA

AMELOBLASTOMAAMELOBLASTOMA
Definition:
1937 - Robinson defined
ameloblastoma as “ a
odontogenic epithelial tumor that
is usually unicentric,
nonfunctional, intermittent in
growth, anatomically benign and
clinically persistent”.

Ameloblastoma
HistoryHistory
•Cassock (1827) : original description of the tumor
•Broca (1868) : 1st
report in the scientific literature
•Falkson (1879) : 1st
complete histological description
• Mallasez (1885): introduce the term adamantinoma
•Churchill (1934): proposed term "ameloblastoma" to
substitute the term "adamantinoma"

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Normal OdontogenesisNormal Odontogenesis
•Stomodeum foregut
(Ectoderm) (endoderm)
•Ectoderm layer + endoderm layer
= Buccopharyngeal membrane (BM)
•Day 27th: rupture of BM
•Dental lamina
•Tooth bud
•Enamel organ (oral ectoderm):Tooth enamel
•Dental papilla (mesenchyme): tooth pulp + dentin
•Dental sac (mesenchyme): cementum + Periodontal ligament
•Week #6: Old oral ectoderm (oral epithelium) basal cells
proliferation
•Dental lamina
•Vestibular lamina

OdontogenesisOdontogenesis
 Bud Stage (Initiation)
•Dental lamina downgrowth of underlying epithelium
mesenchyme
•Buds of deciduos tooth (bud stage)

Cap Stage (Proliferation)
•Proliferation of enamel organ: increase in size & change in shape
•Regions within the enamel organ:
Inner enamel epithelium
Outer enamel epithelium
Stratum intermedium
Stellate reticulum
•Formation of dental papilla:
•Mesemchymal cells beneath the enamel organ
•Formation of dental sac:
•Mesemchymal cells surrounding both the enamel organ &www.indiandentalacademy.com

Bell Stage (Morphodifferentiation)
•At approximately 14 wk
•Cytodifferentiation of the odontoblasts & ameloblasts
•Dental lamina is invaded by mesemchymal cells & begins to
break apart, leaving rests behind (cell rests of Malassez)

Ameloblastoma
Pathogenesis
•Residual ephitelium from odontogenesis process: rests of
mallassez, serraes, remanants from Hertwig’s sheath
•Epithelium of odontogenic cysts (dentigerous cysts)
•Basal cells of surface ephitelium of the jaws

• Disturbances of the developing ephitelium of the
enamel organ
• Heterothropic epithelium from extraoral sites
(specially the pituitary gland)
• Essentially recapitulates the development of the
early tooth forming apparatus without the
formation of enamel or its precursors
VICKERS & GORLIN CRITERIA:
1.Hyper chromatism of basal cell nuclei
2.Reverse polarity (palisading with polarization of
basal cells)
3.Cytoplasmic vacuolization with intercellular spacing
of the lining epithelium.

GROWTH CHARECTERISTICS OF AMELOBLASTOMAGROWTH CHARECTERISTICS OF AMELOBLASTOMA::
Breakthrough Area Cramer et al (1981)
Direct Mechanism
a) The tumor induces lysis of bone matrix at sites where direct contact
occurs
b) Tumor produces a substance which causes lysis of the bone
Indirect Mechanism
a) Tumor obstructs the blood supply to the bone
b) The Tumor mass causes pressure atrophy of the bone
c) The Tumor produces a substance which activates the bone cells
d) The Tumor produces a host reaction which activates the bone cells

Only two possible causes of interaction between tumor and
bone remain:
a) pressure from the tumor creating a peizo-electric effect.
b) metabolic activity provoked by the tumor itself.

Ameloblastoma
 Clinical ClassificationClinical Classification
•Multicystic or conventional solid ameloblastoma – 86%
•Unicystic ameloblastoma – 13%
•Peripheral or extraosseous ameloblastoma - 1%
•Malignant ameloblastoma
•Ameloblastic carcinoma
•Pituitary ameloblastoma

Ameloblastoma
 Radiological ClassificationRadiological Classification
Lagundoye et al (1975) classified as
1. Multiloculated – multicystic
2. Unilocular
3. Septate- trabeculated
4. Solid.

Mcivor (1974) comparing radiographic differences between
ameloblastoma and cyst and other benign tumors of the jaw.
He reported ameloblastoma exhibits
1. Scalloped cortical margins
2. Multilocular appearance
3. Root resorption without displacement of teeth
Ameloblastoma of the maxilla
1. Unilocular appearance more frequently than multilocular
2. Maxillary sinus involved
a. Thickenning of the membrane
b. Cloudiness of the sinus
c. destruction of the wall of the antrumwww.indiandentalacademy.com

Ameloblastoma
 Histopathological ClassificationHistopathological Classification
1. Follicular (simple)
2. Plexiform
3. Acanthomatous
4. Granular
5. Basal cell
6. Desmoplastic
7. Clear cell ameloblastoma

Ameloblastoma
Anatomical classificationAnatomical classification
Ref. Article jn of cranio maxillofacial surgery(1996 vol 24 pg 230
to 236) I.T.Jackson. P.P. Callan Robert A . Forte
Group I : Tumor confined to the maxilla with out involvement
of the orbital floor.
Group II : Tumor involving the orbital floor but not the
periorbital area.
Group III : Tumor involving the orbital content.
Group IV : Tumor involving the skull base.

Multicystic AmeloblastomaMulticystic Ameloblastoma
Clinical Features
•Recur multiple times & can metastasize
•Older group of patients
•Average age presentation: 32.7 - 44 yr.
•Majority of cases involve the mandible
•Kameyama et al: 23:1 ratio of mandibular to maxillary
ameloblastomas

Unicystic AmeloblastomaUnicystic Ameloblastoma
Clinical features
•Robinson & Martinez 1977
•May be associated with an unerupted tooth
Age & Location
Average age: 19.4 yr. To 27.7 yr.
•Almost exclusively in the mandible (few cases in the
maxilla)
•More than 2/3 of the lesion occur in the molar-ramus
region of the mandible
•Molar ramus area: 78% - 75%
•Symphysis area: 13%
•Cuspid-premolar area: 9.7% - 25%

Peripheral AmeloblastomaPeripheral Ameloblastoma
Clinical Features
•Uncommon lesion
•More frequent in the mandible than in the maxilla (2:1)
•Male to female ratio of 1.6:1
•Mean age of diagnosis: 53 yr
•Painless, sessile, firm, exophytic lesion
•Occurs in the soft tissue overlying the alveolar bone
•There is not direct bone involvement, but signs of erosion
or cupping may appear in response to the tumor growth

Malignant AmeloblastomaMalignant Ameloblastoma
Clinical Features
•Rare lesion
•Almost exclusively in the mandible
•Male to female ratio of 1.8:1
•Mean age of diagnosis: 28-32 yr.
•Common sites for metastasis : lungs (75%) spleen, kidney &
ileum

INVESTIGATION:INVESTIGATION:
1.Plain radiograph.
2.Blood Investigation.
3. Biopsy.
4. CT Scan.
5. MRI.
6. Ultrasound.

Radiographic Features
•Radiolucent & well defined lesions
•Sometimes with distinct perilesional sclerotic border
•Common expansion of cortices
•If not associated (impacted tooth)
•Periapical radiolucency with root resorption
•Interradicular pear-shaped radiolucency with adjacent root
divergence
•If associated (impacted tooth)
•Root development of the associated tooth is delayed
•Expansile radiolucency with scalloped margins
•No root resorption of adjacent teeth

Radiographic Features
Mandible:
•Multiple radiolucent loculations (may be unilocular)
•Soap-bubble appearance
•(Syrichitra et al) 27% associated with impacted teeth
•(Syrichitra et al) 40% root resorption of adjacent teeth
Maxilla:
•Uniform or multilocular soap-bubble appearance
•Destruction of antral walls, antral cloudiness & thickening of
sinus membrane

Cohen et al, 1985:
•CT scan is useful to review the involvement of soft tissues &
continuity of lateral and medial cortices when involving
the mandible or maxilla
Heffez et al, 1988:
•MRI is more accurate than CT scan in determining whether a
tumor or scar is present in recurrent lesions

Microscopic Features
Vickers& Gorlin 1970:
•Hyperchromatism of basal cell nuclei of epithelial lining
•Reverse polarization: pallisading and polarization of basal cell
nuclei of epithelial lining away from basement membrane
•Cytoplasmic vacuolation of the basal cells
Ackerman et al :
•Intraluminal UA: ameloblastomatous nodule project into the
cyst lumen without violating the basement membrane &
connective tissue cyst wall
•Intramural UA: ameloblastomatous ephitelium inside of the
connective tissue wall of the cyst

Microscopic Features
Follicular type
•Appearance similar to enamel organ
•Islands of tumor surrounded by polarized layer of tall, columnar,
ameloblast-like cell with nuclei at the opposite pole to the basement
membrane
•Central portion: stellate reticulum
•Cyst and microcysts formation is common
Plexiform type
•Interconnecting strands of ameloblastomatous epithelium
•Thin trabeculae of small darkly staining epithelial cells in a sparsely
cellular connective tissue Stroma
Acanthomatous type:
•Demonstrate squamous metaplasia
•Areas of keratin formation within the stellate reticulum or the central
core of the epithelium
•The tumor resembles the more common follicular typewww.indiandentalacademy.com

Granular cell type:
•The epithelium, in the central portion of the tumor islands, form
sheets of large eosinophilic granular cells
•Epithelial cells with eosinophilic granules within the cytoplasm
•Rare type of ameloblastoma
 Basal cell type:
•The cells are more cuboidal than columnar and they are arranged
in sheets
•The cells are small, darkly stained, arranged in a predominantly
trabecular pattern with little sign of palisading at the periphery
•Resembles the basal cell carcinoma of the skiN
Desmoplastic type:
Extensively dense collagenized stroma
containing small islands of ameloblastomatous epithelium
•The epithelial cells tend to be relatively compact and darkly
stained with little tendency to mimic ameloblasts

Desmoplastic Type
•Within the epithelial islands , the cells may assume an organoid
configuration
•It mainly affect the anterior portion of the jaws, specially the
maxilla
•The radiographic appearances may be more suggestive of fibro-
osseous lesion than an ameloblastoma
Clear cell ameloblastoma
(Waldrom et al 1993)
•Presence of clear cells in the otherwise typical solid
ameloblastoma
•Benign and locally invasive tumor
•Proven metastases
•Clear cell odontogenic ca VS clear cell odontogenic tumor VS
clear cell solid ameloblastoma

TREATMENTS OF AMELOBLASTOMATREATMENTS OF AMELOBLASTOMA
Medical
Radiotherapy
Surgical
Cryotherapy

MEDICAL THERAPYMEDICAL THERAPY
It is not a curative therapy.
It’s only a palliative therapy (has shown reduction in size
of tumour).
Ramadas et al. used a combination of cisplatin,
adriamycin and cyclophosphamide which has shown a
symptomatic and radiologic response.
Gall et al showed improved patient symptoms with
cyclophosphamide & doxorubicin.
Eliasson et al reported a partial tumour response with a
combination of vinblastin sulphate, bleomycin and
cisplatin showed a 50% reduction in tumour size.
Although it has shown good response the tumour had
recurrence and metastasis.www.indiandentalacademy.com

RADIOTHERAPY IN TREATMENT OF AMELOBLASTOMARADIOTHERAPY IN TREATMENT OF AMELOBLASTOMA
Ameloblastoma is generally considered to be a radioresistent
tumour.
In 1982, Reynolds et al. in David G Gardner’s article reasoned that
radiotherapy can reduce the size of an ameloblastoma, primarily
that part of the tumour which has expanded the jaw or broken into
the soft tissues, it does not appear to be an appropriate treatment
for an operable ameloblastoma. Its main use is in inoperable cases,
primarily in the posterior maxilla.

SURGICAL TREAMENTSURGICAL TREAMENT
Let’s say what we cut
Enucleation:
means that the lesion is separated from bone without
bone removal along a tissue plane between the connective tissue
envelope and the surrounding bone. The only bone that is
removed is that which is required for surgical access. This term
does not necessarily imply that the lesion is removed in a single
piece as the lesion may fragment or need to be segmented to be
completely enucleated.
Marsupialization:
is a surgical exteriorization of a pathologic lesion
usually a cyst by removal of a portion of the overlying tissue to
expose the internal surface of the lesion.

Curettage:
means that the lesion is removed from bone and that
an inexact, immeasurable, variable amount of surrounding bone
is also removed. It is used when the lesion is friable or does not
have an encapsulating membrane.
Resection without continuity defect:
means that the lesion and a defined, measurable
perimeter of adjacent bone is removed along with the lesion and
the bony continuity is maintained.
Resection with continuity defect:
means that the lesion is resected with a
predetermined, measurable perimeter of adjacent bone and with
interruption of bony continuity.

Disarticulation:
is a form of resection with continuity defect that
includes the removal of mandibular condyle from the TMJ.
Recontouring:
is a surgical reduction or alteration of size or shape of
bony pathological lesion. The procedure is planned to restore the
surface to a normal contour and may or may not eradicate the
lesion.

MAXILLAMAXILLA
Group 1: Partial maxillectomy.
Group 2: Total maxillectomy.
Group 3: Total maxillectomy with orbital exenteration.
Group 4: Total maxillectomy with anterior skull base
resection and orbital exenteration as indicated

INCISIONS:
1) Transoral and Transpalatal approach
2) Mid facial degloving
3) Weber Fergusson incision ( Dieffenbach )
4) Weber Fergusson incision with lynch extension
5) Weber Fergusson incision with lateral subciliary extension
6) Weber Fergusson incision with subciliary and supraciliary
extension
7) Weber Fergusson incision with infraorbital extension
8) Weber Fergusson incision with Brow extension

 MANDIBLEMANDIBLE
1) Midline lip splitting incision
2) Midline lip splitting incision with modified MacFee
incision

 RECONSTRUCTION:RECONSTRUCTION:
Maxilla
Group1:Maxillectomy with or without skin graft and dental prosthesis or
free tissue transfer
Group 2:Maxillectomy and skull base resection and free tissue transfer
SPLIT THICKNESS SKIN GRAFT &DENTAL OBTURATOR
SOFT-TISSUE FLAPS & BONE GRAFT
NOSE PROSTHESIS ON BAR CONNECTED TO,
OSTEOINTEGRATED IMPLANT

Mandible
Use of Kirschner wire
Metallic (titanium or stainless steel) or Plastic (dacron, polyurethane)
trays with Cancellous bone
Bone Graft ( iliac, rib, scapular spine, calvarium)
Microvascular transfers of bone and soft tissues
Pedicle and free osteomyocutaneous flaps
Metallic plates
Use of resected mandible reused after freezing in liquid nitrogen

RECURRENCE OF AMELOBLASTOMA:RECURRENCE OF AMELOBLASTOMA:
For a large part, reflects the inadequacy or failure of primary
surgical procedure.
ENUCLEATION & CURETTAGE:-65%-75%
RADICAL RESECTION:-5%-15%

METASTASIS OF AMELOBLASTOMA:METASTASIS OF AMELOBLASTOMA:
DEFINITION:
The active or passive dissemination of neoplastic disease from
the site of origin to a distant site or organ in the host
METHODS OF SPREAD:
1.HEMATOGENOUS SPREAD
2.LYMPHATIC ROUTE
3.ASPIRATION
SITES OF METASTASIS:
1.PULMONARY METASTASIS
2.CERVICAL LYMPH NODES
3.BRAIN
4.BONE &SOFT TISSUEwww.indiandentalacademy.com

REFERENCESREFERENCES:
Books:-
Daniel M Laskin
Peterson, Ellis, Hupp, Tucker
Peter Ward Booth
John M Lore’
Lucas Pathology
Marks Pathology
Archer

Journals:-
JO Oral Surgery, Oral Medicine, Oral Pathology
Let’s say what we cut(Peterson) Vol.76 No.4 July1993
Surgical management of ameloblastoma(Peterson) Vol.81 No.4 April1996
Some current concepts on pathology of ameloblastoma(Carl M Allen)
Vol.82 No.6 Dec1996
Metastasis of Ameloblastoma(Carl M Allen) Vol.88 No.2 Aug1999
JO Craniomaxillofacial Surgery
An anatomical classification of maxillary ameloblastoma as an aid to surgical
treatment
I T Jackson, P P Callan, Robert A Forte (1996) 24. 230 236
JO Max.Fac.Surg.
Growth characteristics of multilocular ameloblastoma(Hellmuth Muller,
Peter J Slootweg) 1985

Unisystic Ameloblastoma of Mandible(1997)
Peripheral Ameloblastoma(1994,1995)
Marsupialization of cystic ameloblastoma(1995)
FNAB of intraosseous jaw lesions(1999)
Recurrent ameloblastoma of the jaws(1998)
Ameloblastoma-controversial approach to therapy(1985)
Management of ameloblastoma(1993)
Use of liquid nitrogen cryotherapy in the management of locally
aggressive bony lesion(1993)
Conservative surgical treatment of mandibular ameloblastoma(1978)

Ameloblastoma / oral surgery courses

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Ameloblastoma / oral surgery courses