Ameloblastoma is a true neoplasm originating from the enamel organ, classified by clinical and histological types, with a notable prevalence in the mandible and a mean diagnosis age of 30-39 years. The tumor displays varying growth patterns and can have high recurrence rates, with management strategies ranging from enucleation to more aggressive surgical interventions. Malignant variants, including ameloblastic carcinoma, present significant challenges due to their aggressive nature and potential for metastasis, primarily to the lungs and cervical lymph nodes.

1. AMELOBLASTOMA
SAKSHAT LAMICHHANE

2. INTRODUCTION
 Is a true neoplasm of enamel organ type
tissue which does not undergo differentiation
to point of enamel formation
 Robinson described tumor as usually
unicentric, nonfunctional, intermittent in
growth, anatomically benign and clinically
persistent.

3.  Previously called adamantinoma –
malassez in 1885
 Since this term implied the formation of hard
tissue, and no such material was present in
this lesion, it was replaced with term
ameloblastoma suggested by churchill in
1934

4. ORIGIN
 Cell rests of dental organ, either remnants of dental lamina or remnants
of hertwig’s sheath
 Epithelium of odontogenic cysts (dentigerous cysts and odontoma)
 Enamel organ
 Basal cell of surface epithelium of jaws
 Heterotopic epithelium of pituitary gland
 Reduced enamel epithelium

5. PATHOGENESIS
• Low proliferation rate (ki67)
• Over expression of
antiapoptotic proteins (bcl-2,
bclxl)
Cell cycle
related
factors
• Overexpression of interface
protein (fibrinoge growth factor)
• Overexpression of matrix
metallo groth factor proteinase)
Interface
factors

6. CLASSIFICATION
 Based on clinical types
1. Conventional solid or multicystic (about 86%
of all cases)
2. Unicystic (about 13% of all cases)
3. Peripheral (extraosseous) (about 1% of all
cases)

7.  Based on clinical behaviour
Benign
1.solid/multicystic
2.unicystic
3.peripheral
malignant
1.malignant ameloblastoma
2.ameloblastic carcinoma

8.  Based on loaction
Intraosseous/ central
Extraosseous/ peripheral

9.  Based on histological classification
1.Follicular pattern and its variant
granular
acanthomatous
basal cell variant
2. plexiform pattern
3. unicystic ameloblastoma
luminal
intraluminal
mucosal

10. CONVENTIONAL SOLID OR MULTICYSTIC
INTRAOSSEOUS AMELOBLASTOMA
 CLINICAL FEATURES
• Age- 10-90 years
• Average age of diagnosis
30-39 years
• No sex predilection
• Race: more common in blacks
than in white race.
• Site- Mandible (molar-angle-ramus area three
times more commonly than premolar and anterior
region combined)

11. CLINICAL PRESENTATION
 Slow growing,
painless, bony hard
swelling
 Facial asymmetry
 Large lesions- mobile
teeth, pain and
paraesthesia
 Locally invasive
 Infiltrate medullary
spaces causing
erosion of cortical
bone

12. RADIOGRAPHIC FEATURES
 multilocular radiolucent lesion
 “soap bubble” appearance (when the
radiolucent loculations are large) or as
being “honeycombed”(when the
loculations are small)
 Compartmented appearrances with
septa of bone extending into
radiolucent tumor mass
 Buccal and lingual cortical expansion
 Resorption of the roots of teeth
adjacent to the tumor is common
 The margins of these radiolucent
lesions, however, often show irregular
scalloping

16. DESMOPLASTIC AMELOBLASTOMA
 occur in the anterior regions
of the jaws particularly the
maxilla
 resembles a fibro-osseous
lesion because of its mixed
radiolucent and radiopaque
appearance
 mixed radiographic
appearance is due to
osseous metaplasia within
the dense fi brous septa that
characterize the lesion, not
because the tumor itself is
producing a mineralized
product

17. DIFFERENTIAL DIAGNOSIS
 Odontogenic keratocyst- displaced thinning
of cortical bone and associated with
unerupted tooth
 Myxoma- condyle involved- spontaneous
fracture
 Odontogenic myxoma- soap bubble
appearance, multiple loculayion
 Radicular cyst – associated with apex of
tooth

18. HISTOLOGICAL TYPES
AmeloblastomaPlexiform
Acanthomatous
Granular Basal cell type
Desmoplastic
Follicular

19. VICKER AND GORLIN CRITERIA FOR
AMELOBLASTOMA
Hyperchromatism of basal cell nuclei.
Palisading of basal cell with polarization of
nuclei away from basement membrane (
reverse polarity)
Cytoplasmic vacuolization of basal call

20. FOLLICULAR PATTERN
 Most common
 Islands of epithelium resemble enamel organ
epithelium in a mature fibrous connective tissue
stroma
 epithelial nests consist 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 (reversed polarity). In other areas, the
peripheral cells may be more cuboidal and resemble
basal cells.
 Cyst formation is common

23. PLEXIFORM PATTERN
 consists of long, anastomosing cords or 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.
 The supporting stroma tends to be loosely
arranged and vascular.
 Cyst formation is relatively uncommon
 When it occurs, it is more often associated with
stromal degeneration rather than cystic change
within the epithelium

26. ACANTHOMATOUS PATTERN
 When extensive squamous metaplasia, often
associated with keratin formation, occurs in
the central portions of the epithelial islands of
a follicular ameloblastoma, the term
acanthomatous ameloblastoma
 may be confused with squamous cell
carcinoma or squamous odontogenic

29. GRANULAR CELL PATTERN
 Transformation of groups of lesional epithelial cells to
granular cells.
 cells have abundant cytoplasm filled with eosinophilic
granules that resemble lysosomes ultrastructurally and
histochemically.
 Lysosomal aggreration caused by
• dysfunction of either a lysosomal enzyme or
• lysosome associated protein involved in enzyme
activation, enzyme targeting or lysosomal biogenesis
• Increased apoptotic cell death by neighbouring neoplastic
cells
 Aggressive lesion and marked recurrence

32. DESMOPLASTIC PATTERN
 small islands and cords of odontogenic epithelium in a
densely collagenizedstroma.
 Immunohistochemical studies have shown increased
production of the cytokine known as transforming growth
factor-b (TGF-β) in association with this lesion,
suggesting that this may be responsible for the
desmoplasia.
 Peripheral columnar ameloblast-like cells are
inconspicuous about the epithelial islands
 Dense collagenous stroma that may appear hyalinized
and hypocellular
 Epithelium squeezed and fragmented by dense stroma
 Grow in thin strand and cords of epithelium stretched out
in kite tail like appearance

35. BASAL CELL PATTERN
 Least common type
 composed of nests of uniform basaloid cells,
and they histopathologically are very similar
to basal cell carcinoma of the skin.
 No stellate reticulum is present in the central
portions of the nests.
 The peripheral cells about the nests tend to
be cuboidal rather than columnar

37. HYBRID AMELOBLASTOMA
 Extremely unusual
 Desmoplastic varient with areas of classical
follicular/plexiform varient
 Some cases- tumor cells with granular
transformation along with areas of follicular
and plexiform ameloblastoma while some
show basaloid changes

38. HEMANGIOMATOUS AMELOBLASTOMA
 Less common
 Connective tissue stoma with many blood
filled spaces or large endothelial lined
capillaries
 Theories
 Hamartomatous malformation
 trauma
 Separate neoplasm or collision tumor

39. PITUITARY AMELOBLASTOMA
 Neoplasm involving central nervous system
 Common- childhood and adolescence
 Origin- unobliterated portions of fetal
craniopharyngeal duct, derived from Rathke’s
pouch and epithelial remnants of this duct
are common on adult

40. ADAMANTINOMA OF LONG BONES
 Superficial microscopic resemblance to
ameloblastoma of jaws
 Sites
tibia(common)
ulna, femur, fibula

41. OTHER VARIENTS
 Acanthomatous ameloblastoma
 keratoameloblastoma
 Papilliferous keratoameloblastoma

42. TREATMENT AND PROGNOSIS
 simple enucleation
 curettage to en bloc resection
 Recurrence rates of 50% to 90%

43. UNICYSTIC AMELOBLASTOMA
 10% to 46% of all intraosseous ameloblastomas
 Origin
1. de novo as a neoplasm or
2. neoplastic transformation of nonneoplastic cyst
epithelium
Criteria for diagnosis
 Demonstration of single( often macro) cystic sac
 Odontogenic(ameloblastomatous) epithelium present
usually in focal area

44. CLINICAL FEATURES
 younger patients
 mandible, posterior regions
 Asymptomatic
 large lesions may cause a painless swelling
of the jaws.

45. RADIOGRAPHIC FEATURES
 circumscribed radiolucency
that surrounds the crown of
an unerupted mandibular
third molar clinically
resembling a dentigerous
cyst.
 sharply defined radiolucent
areas and are usually
considered to be a
primordial, radicular, or
residual cyst, depending
onthe relationship of the
lesion to teeth in the area.

46. HISTOPATHOLOGIC FEATURES
luminal
unicystic
ameloblastoma
intraluminal
unicystic
ameloblastoma
mural unicystic
ameloblastoma
Three histopathologic variants

48. LUMINAL UNICYSTIC AMELOBLASTOMA
 tumor is confined to the
luminal surface of the cyst
 fibrous cyst wall with a lining
that consists totally or partially
of ameloblastic epithelium
 basal layer of columnar or
cuboidal cells with
hyperchromatic nuclei that
show reverse polarity and
basilar cytoplasmic
vacuolization
 Overlying epithelial cells are
loosely cohesive and resemble
stellate reticulum

50. INTRALUMINAL UNICYSTIC AMELOBLASTOMA
 one or more nodules of
ameloblastoma project
from the cystic lining into
the lumen of the cyst
 Nodules may be relatively
small or largely fill the
cystic lumen
 plexiform unicystic
ameloblastomas- nodule
of tumor that projects into
the lumen demonstrates
an edematous, plexiform
pattern

52. MURAL UNICYSTIC AMELOBLASTOMA
 Islands of
ameloblastomatous
epithelium isolated in the
connective tissue wall

54. TREATMENT AND PROGNOSIS
 Enucleation and curettage
 Recurrence rates of 10% to 20%

55. PERIPHERAL (EXTRAOSSEOUS)
AMELOBLASTOMA
 Uncommon
 1% to 10% of all ameloblastomas.
 arises from rests of dental lamina beneath
the oral mucosa or from the basal epithelial
cells of the surface epithelium.
 Histopathologically same features as the
intraosseous form of the tumor.

56. CLINICAL FEATURES
 middle-aged persons
(average 52 years)
 Sites- posterior gingival
and alveolar mucosa,
common in mandibular
than in maxillary areas.
 painless,
 nonulcerated
 sessile or pedunculated

57. HISTOPATHOLOGIC FEATURES
 islands of ameloblastic
epithelium that occupy the
lamina propria underneath the
surface epithelium
 Plexiform or follicular patterns
are the most common
 Connection of the tumor with
the basal layer of the surface
epithelium is seen in about
50% of cases

58. TREATMENT AND PROGNOSIS
 respond well to local surgical excision
 local recurrence has been noted in 15% to
20% of cases

59. MALIGNANT AMELOBLASTOMA AND
AMELOBLASTIC CARCINOMA
 malignant ameloblastoma
a tumor that shows the histopathologic
features of ameloblastoma, both in the primary
tumor and in the metastatic deposits
 ameloblastic carcinoma
an ameloblastoma that has cytologic
features of malignancy in the primary tumor,in a
recurrence, or in any metastatic deposit

60. CLINICAL AND RADIOGRAPHIC
FEATURES
 age - 4 to 75 years (mean age,
30 years)
 Metastases from
ameloblastomas are most
often found in the lungs-
aspiration or implant
metastases
 Cervical lymph nodes are the
second most common site for
metastasis of an
ameloblastoma
 Ameloblastic carcinomas are
often more aggressive
lesions,with ill-defi ned margins
and cortical destruction

61. HISTOPATHOLOGIC FEATURES
 primary jaw tumor and the
metastatic deposits show
features that of ameloblastomas
with a completely benign local
course
 addition to cytologic features of
malignancy
• increased nuclear-to-
cytoplasmic ratio,
• nuclear hyperchromatism,
• presence of mitoses
• Necrosis in tumor islands
 areas of dystrophic calcification
may be present.

62. TREATMENT AND PROGNOSIS
 Prognosis poor
 50% of the patients with
documented metastases
and long-term follow-up
have died of their disease
 Ameloblastic carcinoma
have demonstrated a
uniformly aggressive
clinical course, with
perforation of the cortical
plates of the jaw and
extension of the tumor into
adjacent soft tissues.

63. REFERENCES
 Text book of oral pathology- Shafer 8th
edition.
 Text book of oral & maxillofacial pathology-
Neville 3rd edition.
 https://www.researchgate.net/figure/209389225
_fig10_Fig-10-Types-of-growth-in-Unicystic-
Ameloblastoma-1-Luminal-2-Intraluminal-3
 https://www.facebook.com/hackdentistry