Ameloblastoma ,odontogenic tumors/ dental courses

Definition
 Robinson defined it as“ A tumor that is usually unicentric,
intermittent in growth, anatomically benign and clinically
persistent”
 Second most common Odontogenic Tumor ( 1st –odontoma)
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Origin
 The exact origin of ameloblastoma is not known
 Enamel organ
 Cell rests of Serres
 Cell rests of Malassez
 Oral mucosa
 Epithelial lining of odontogenic cysts

Site of occurrence
 Mandible is the most commonly affected area
 Molar-Angle-Ramus area is involved three times more
commonly than are the premolar and anterior regions
 Maxillary- anterior = posterior region.

 Maxillary -slightly older patients than do mandibular
 Asians –Posterior region
 Whites or blacks -Anterior region

Clinical Presentation
 Slow growing with few or no
signs in early stages
 Most commonly present with
chief complaints of swelling
and facial asymmetry.
 The swelling is typically
asymptomatic, pain is an
occasional presenting sign.

Continued growth-
Ulceration of the
overlying mucosa
Local effects –
o Tooth mobility
o Occlusal alterations
o Failure of eruption of
teeth.

Radiographic Presentation
 Multilocular or ‘‘soap-
bubble’’radiolucency.
 Smooth bordered unilocular
radiolucency
 A unilocular lucency with a
scalloped or lobulated border
 A poorly delineated mixed
lucentopaque lesion

Radiographic Presentation
 Unilocular lesions associated
with an impacted tooth
 Younger patients
 Surrounding the crown of the
impacted tooth in a dentigerous
cyst type relationship

Macroscopic appearance
 Cylindrical / Fusiform swelling expanding bone
 Perforation of the cortex
 Greyish white/ Greyish yellow mass
 Readily cut containing no calcifications
 Some cases solid and in some cystic spaces may be
present
 Straw colored fluid / Semi solid material may be present
 Multiple teeth may be present

Histopathology
 Two main patterns of ameloblastoma are recognized
 Follicular
 Plexiform
 Other Histopathologic subtypes of ameloblastoma are
recognized:
 Acanthomatous,
 Granular cell,
 Basal cell,
 Desmoplastic,

 Clear cell,
 Keratoameloblastoma
 Papilliferous ameloblastoma
 Hemangiomatous ameloblastoma
 Mucous cell differentiation

 The histologic subtype may have prognostic
implications for recurrence.
 The follicular type of ameloblastoma had the highest rate of
recurrence at 29.5%.
 The acanthomatous type of ameloblastoma showed only a
4.5% recurrence rate.
 The plexiform subtype showed a 16.7% recurrence rate.
 Recurrences documented in granular cell , basal cell,&
Desmoplastic subtypes

Follicular ameloblastoma
 Most commonly encountered variant
 The follicular ameloblastoma tends to grow primarily
in islands
 The islands of tumor shows central cystic
degeneration

Classic features of ameloblastoma originally
were described by Vickers and Gorlin in 1970.
 Darkly staining periphery composed of
tall columnar cells
 Hyperchromatic nuclei.
 A small clear vacuole can be seen between the nucleus &
the basement membrane.
It mimic the normal embryologic
development of the tooth bud at
the stage of enamel matrix
production.

 The central cells of follicle are typically
polyhedral to spindle shaped. When spindle
shaped, they often have angular nuclei and poorly
defined cytoplasm, with delicate fibrillar
cytoplasmic processes that contact adjacent cells
 Produces a loosely cohesive meshwork that
closely simulates the stellate reticulum seen in
the developing enamel organ.

Acanthomatous ameloblastoma
 May closely resemble the follicular type. It tends to
grow primarily in an island-like pattern.
 It differs from the follicular ameloblastoma in the
nature of the central cells within the tumor islands.
 In the acanthomatous ameloblastoma, squamous
cells replace the stellate reticulum-like cells. The
squamous cells nearly always show a tendency to
keratinization

 Parakeratin typically is seen. This effect produces
a distinctive pink color change compared with
the deeply basophilic staining maintained in the
peripheral columnar cells.
 A layer of stellate reticulum-like cells that separates
the peripheral columnar cells from the central
squamous areas often is seen.
 Central cystic change can be seen in larger tumor
islands.

Granular cell ameloblastoma
 Characteristic feature is the presence of
granular cells in the central portion of the
epithelial islands, strands, and cords
 The granular cells tend to be large and have an
oval to polyhedral outline. The nucleus is
displaced to the periphery of the cells.
 Prominent coarse granules pack and distend the
cytoplasm, imparting the distinctive appearance
responsible for the name of these cells.

 The cytoplasmic granules tend to stain weakly
eosinophilic
 A thin rim of stellate reticulum-like cells that
separates the granular cells from the peripheral
columnar layer may or may not be present.

Ameloblastoma ,odontogenic tumors/ dental courses

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