AMELOBLASTOMA - a benign odontogenic tumor

1. Dr.Faisal K A
Tutor
Malabar Dental College and Research Centre

2.  CONTENTS
 Introduction
 Pathogenesis
 Clinical classification
 Clinical features
 Radiographic features
 Histological features
 Management
 Prognosis
 Conclusion

3. INTRODUCTION
 (adamantinoma , adamantoblastoma )
 Ameloblastoma is a true neoplasm of enamel
organ type tissue which does not undergo
differentiation to a point of enamel formation
Definition
 ‘’Being a tumor that is usually unicentric , non
functional ,intermittent in growth ,
anatomically benign and clinically persistent’’
Robinson

4.  The term ameloblastoma as applied to the
particular tumor was suggested by Churchill in
1934
 It is the second most common odontogenic
neoplasm

5.  PATHOGENESIS
 Tumor conceivably may be derived from,
 Cell rests of the enamel organ, either remnants
of the dental lamina or Hertiwig’s sheath,
epithelial rests of malassez
 Epithelium of odontogenic cysts
 Disturbances of the enamel organ
 Basal cells of the surface epithelium of the jaw
 Heterotropic epithelium in other parts of the
body ,especially pituitary gland

6.  Unicystic ameloblastoma
 Conventional or multicystic or solid
ameloblastoma
 Peripheral (extraosseous)ameloblastoma
 Malignant ameloblastoma
 Pituitary ameloblastoma(craniopharyngioma,
or Rathke’s pouch tumour)

7.  Conventional solid or multicystic intraosseous
ameloblastoma
 Clinical features
 It is rare in children younger than age 10
 Prevalence in the third to seventh decade of life
 No sex predilection
 80% to 85% of the cases occur in mandible ,most
often in molar ascending ramus area
 Often asymptomatic and smaller lesions are
detected only during a radiographic examination

8.  A painless swelling or expansion of the jaw is
the usual clinical presentation
 If untreated ,then the lesions may grow slowly
to massive or gortesque proportions
 Pain and parasthesia are uncommon

9.  Radiographic features
 Multilocular radiolucent lesion
 Soap bubble appearance or as being honey
combed
 Buccal and lingual cortical expansion is
frequently present
 resorption of the root of the adjacent tooth
 Margins of the radiolucent lesion show
irregular scalloping

11.  Histopathologic features
 Conventional solid ameloblastoma show
remarkable tendency to undergo cystic change
,grossly most tumors have varying combination of
cystic and solid features
 This includes
 Follicular
 Plexiform pattern
 Acanthomatous
 Granular cell
 Desmoplastic
 Basal cell type

12.  Follicular pattern
 Most common and recognizable
 Islands of epithelium resemble enamel organ
epithelium in a mature fibrous connective
tissue stroma
 The epithelium nests consists of a core of
loosely arranged angular cells resembling the
stellate reticulum of an enamel organ
 A single layer of tall columnar ameloblast like
cells surrounds this central core
 The nuclei of these cells are located at the
opposite pole to the basement membrane

13.  The peripheral cells may be more cuboidal and
resemble basal cells
 Cyst formation is common and vary from
micro cyst ,which form within the epithelial
islands to large macroscopic cysts

14.  Plexiform pattern
 Consists of long anastomosing cords of larger
sheets of odontogenic epithelium
 The cords or sheets of epithelium are bounded
by columnar or cuboidal ameloblast like cells
surrounding more loosely arranged epithelial
cells
 Supporting stroma tends to be loosely arranged
and vascular
 Cyst formation is usually uncommon
 More often associated with stromal
degeneration rather than cystic changes

17.  Acanthomatous pattern
 When extensive squamous metaplasia ,often
associated with keratin formation, occurs in
central part of the epithelial islands of a
follicular ameloblastoma ,the term
acanthomatous ameloblastoma is sometime
applied

18.  Granular cell pattern
 it may show transformation of groups of
lesional epithelial cells to granular cells
 These cells have abundant cytoplasm filled
with eosinophilic granules that resemble
lysosomes ultra structurally and
histochemically
 This variant is seen in young patient
 More aggressive type
 High chance of recurrence rate ans metastasis

20.  Desmoplastic pattern
 This type contains small islands and cords of
odontogenic epithelium in a densely
collagenized stroma
 Immunohistochemical studies have shown
increased production of the cytokine known as
transforming growth factor beta
 Peripheral columnar ameloblast like cells are
inconspicuous about the epithelial islands

22.  Basal cell pattern
 Least common
 Composed of nests of uniform basaloid cells,
and they histopathologically similar to basal
cell carcinoma of the skin
 No stellatereticulam present in the central
portion of the nests
 Peripheral cells are cuboidal

23.  Unicystic ameloblastoma
 Clinical features
 Seen most often in younger patients, second
decade of
Life
 90% cases are found in the mandible, usually in
the posterior region
 Asymptomatic , large lesions may cause a
painless swelling of the jaw

24.  Radiographic features
 Lesions typically appears as a circumscribed
radiolucency that surround the crown of an
unerupted mandibular third molar
 In some instances , the radiolucent area may
have scalloped margins

26.  Histopathological features
 Three variants
 Luminal unicystic ameloblastoma
 Intraluminal unicystic ameloblastoma
 Mural unicystic ameloblastoma

27.  Luminal unicystic ameloblastoma
 The tumor is confined to luminal surface of the
cyst
 Lesion consists of fibrous cyst wall with lining
composed totally or partially of ameloblastic
epithelium
 The lining demonstrate a basal layer of columnar
or cuboidal cells with hyper chromatic nuclei with
revers polarity and cytoplasmic vacuolization
 The upper epithelial cells are loosely cohesive and
resemble stellate reticulum

28.  Luminal
 Intraluminal

29.  Intra luminal
 One or more nodules of ameloblastoma project
from the cystic lining into the lumen of the cyst
 These nodule may small or largely fill the
cystic lumen
 In some cases the nodule of tumor that project
in to the lumen demonstrate an edematous
,plexiform pattern seen in the conventional
ameloblastoma

30.  Mural unicystic ameloblastoma
 The fibrous wall of the cyst is infiltrated by
typical follicular or plexiform ameloblastoma

31.  Treatment and prognosis
 Enucleation and curettage
 Recurrence rate 10 -20%

32.  Peripheral ameloblastoma
 Uncommon
 Arises from rests of dental lamina beneath the
oral mucosa
 Clinical feature
 Painless ,non nucleated ,sessile or
pedunculated gingival or alveolar mucosal
lesion
 Most examples are smaller than 1.5cm

33.  Most often seen in middle aged patients
 Commonly found on the posterior gingival and
alveolar mucosa
 More common in mandible
 Superficial alveolar bone become slightly
eroded

34. Histopathologic features
 Islands of ameloblastic epithelium that occupy
the lamina propria underneath the surface
epithelium
 The proliferating ameloblastoma show any of
the features described for the conventional
ameloblastoma
Treatment and prognosis
 Local surgical excision

35.  Malignant ameloblastoma
 Clinical features
 Age range from 6 to 61 years
 No sex predilection
 Metastasis from ameloblastoma are found most
in the lungs(aspiration or implant metastases )
 Second-cervical lymph nodes
 Spread to vertebrae, bones and viscera has also
occasionally been confirmed

36.  Radiographic finding
 Same as nonmetastasizing ameloblastoma
 More aggressive lesion with ill defined margins
and cortical destruction
 Histopathologic features
 Microscopic feature of ameloblastoma in
addition to cytologic features of malignancy.
 Increased nuclear –cytoplasmic ratio
 Nuclear hyperchromatism
 Presence of mitoses
 Necrosis in tumor islands and dystrophic
calcification

37.  Treatment and prognosis
 Poor prognosis
 Aggressive resection

38. Pituitary ameloblastoma(craniopharyngioma, or Rathke’s
pouch tumour)
 Neoplasm of the CNS that grows in a
psedoencapsulated mass in the suprasellar or
intrasellar area after destroying the pituitary gland
 Most common tumour of childhood and
adolescents with an average age of 3-23 years(25%
of all CNS tumours)
 Derived from craniopharyngeal duct formed by
Rathke’s pouch(oral ectoderm)

39.  Histologically similar to oral ameloblastoma
but also contains irregular calcified masses as
well as occasional foci of metaplastic bone or g

40.  Treatment and prognosis
 En bloc resection or marginal resection
 Segmental Resection
 En bloc resection or marginal Resection

41.  Segmental Resection
• If cortical bone is resorbed and penetrated , the
resection should include periosteal layer
• A thin inferior border of the mandible in the first
procedure may fracture ,if a reconstruction plate is
not used to span and support the segment .
• If the complete excision of the tumor is ascertained
by clinical and radiographic examination of
specimen or intraoperative frozen section ,then
immediate reconstruction can be undertaken

42.  If there is uncertainty about resection margins
,reconstruction should be delayed until no recurrence
is seen ,at least after six months postoperatively
 Adequate soft tissue coverage should be available ,if
immediate reconstruction is planned
 It can be done by using an autogenous free bone grafts
Or bank allogenic bone crib and autogenous bone
marrow with a reconstruction plate
 Reconstruction plate with/without condylar prosthesis
can be used in very old patients
 If sufficient soft tissue is not available ,a vascularized
composite pedicle graft of bone and myocutaneous
tissue can be used

44.  In maxilla –aggressive resection is carried out
Jackson and Callon Forte have given guide lines
depending upon anatomical extents
 Tumor confined to maxilla without orbital floor
involvement-partial maxillactomy
 Tumor involving the orbital floor ,but not the
periorbital area-total maxillectomy
 Involving orbital contents-total maxillectomy
with orbital extenteration
 Involving the skull-along with skull base
resection –neurosurgical procedure

45.  PERIPHERAL OSTEOTOMY
 Complete excision of tumour with a span of bone is retained-
preserves the continuity of the jaw
 Involves careful exposure and curettage of all
the visible tumour.
 Toremove mergins rotary instruments are used
 Advantage: preservation of vital structures and
bone integrity
 Disadvantage: seeding of the tumour into
surrounding tissues

46.  Cautery
 Desiccation or electrocoagulation of the lesion,
including various amounts of surrounding
normal tissue .
 Not commonly used, 50% recurrence rate
 Secondary ischemia and necrosis may occur

47.  Conclusion
 Ameloblastoma is the most common clinically
significant odontogenic tumor having three
different clinicoradiographic presentation

48.  TEXT BOOK OF ORAL AND
MAXILLOFACIAL SURGERY- CHAPTER 44-
NEELIMA ANIL MALIK
 TEXT BOOK OF ORAL AND
MAXILLOFACIAL SURGERY- S M BALAJI

49. Thank you