Dr. Gaurav S. Salunkhe
Oral & Pathology
Clinical Case Presentaion
Ameloblastoma – English word amel, meaning
enamel+ the Greek word blastoma meaning
Odontogenic tumors represent a spectrum of
lesion ranging from malignant(rare) and benign
neoplasm to dental hematomas all arising from
odontogenic residues ie. Odontogenic epithelium
Occasionally an odontogenic tumor develops
from a pre-existing developmental cyst (AOT,
Ameloblastoma from dentigerous cyst)
Biopsy No. 107/13
Case No. 884618
Ref.by: Dr. Bharat Department : OS
Name of the Patient: Kosha Gandhi
Age : 30yrs Sex: Female
Chief Complaint: swelling on the right side of lower jaw
since 1 year.
Provisional Diagnosis: Ameloblastoma.
Based on histological features the diagnosis was
given as Plexiform Ameloblastoma.
(adamantinoma, adamantoblastoma, multilocular cyst)
It is a true neoplasm of enamel organ type tissue
which does not undergo differentiation to the point of
Defined as: ‘USUALLY UNICENTRIC,
NONFUNTIONAL, INTERMITTENT IN GROWTH,
ANATOMICALLY BENIGN AND CLINICALLY
PERSISTENT’. By Robinson.
The term ameloblastoma was suggested by Churchill
in 1934 to replace the term Adamantinoma, coined
by Malassez in 1885.
The earlier workers noted the resemblance
between the odontogenic apparatus and the
ameloblastoma and suggested that the neoplasm
has derived from a portion of this apparatus or
from cells potentially capable of forming dental
Most authors believed that the ameloblastoma to
be of varied origin, thus the tumor conceivably
may be derived from
1. Cell rest of the enamel organ (remnants of the
dental lamina, Hertwig’s sheath, the epithelial
rest of Malassez).
2. Epithelium of odontogenic cysts. (dentigerous
3. Disturbance of developing enamel organ.
4. Basal cell of the surface epithelium of the jaw.
5. Heterotopic epithelium in other parts of the
body, specially the pituitary gland.
The unicystic ameloblastoma represent those cystic
lesion that shows clinical, radiographic, or gross
features of a jaw cyst, but on histologic examination
shows a typically ameloblastic epithelium.
The lining part of the cavity may or may not show
luminal and or mural tumor growth.
It is variant of ameloblastoma comprising of 10% to
15% of all intra bony ameloblastoma.
The exact histogenesis is not clear.
It has been suggested that it arise from as a result of
neoplastic transformation of the epithelial lining of
dentigerous cyst or any other type of dental cyst.
A high percentage of these lesions are associated
with impacted tooth and most commonly cited
provisional diagnosis is dentigerous cyst.
The recurrence rate is low, and thus indicating
Unicystic ameloblastoma is characterized by
one or more of the following features:
1. Vickers & Gorlin criteria
2. Nodules of tumor projecting intraluminal.
3. Epithelium proliferating into connective
4. Islands of ameloblastoma occurring isolated
in connective tissue wall.
In some instances, the ameloblastic epithelium
may be proliferative, with extension of the
ameloblastic epithelium into the lumen of the
cystic cavity. This feature has been termed as
This growth resembles Plexiform ameloblastoma,
thus some lesion have been referred to as
Plexiform unicystic ameloblastoma.
Ackermann classification of
Group 1- Luminal unicystic ameloblastoma.
Tumor confined to the luminal surface of the cyst.
Group 2- Intra-luminal unicystic ameloblastoma.
Nodular proliferation into the lumen without
infiltration of tumor cells into the connective tissue
Group 3- Mural unicystic ameloblastoma.
Invasive islands of ameloblastomatous epithelium
in the connective tissue wall not involving the
1. Mostly seen in younger individuals.
2. Mostly seen in mandible.
3. Posterior region. Molar-Ramus region
1. Well defined, radiolucent lesion, with minimal
peripheral sclerotic border.
2. Mimics dentigerous cyst.
3. Associated with impacted/unerupted 3rd molar.
4. In advance stage thinning of cortical bone can
Peripheral ameloblastoma is a uncommon/rare
type of odontogenic tumor.
It develops in the soft tissue of the gingiva and
It exhibits an innocuous clinical behaviour.
It is non-invasive.
It accounts for 1-5% of all ameloblastoma.
Mostly seen in younger individual.
Males > Females.
Mostly seen in premolar region.
The lesion appears as nodule on the gingiva or
Size ranges from 3mm– 2cm in diameter.
Recurrence is uncommon, except when it is
The epithelial component of the neoplasm proliferate
to form disconnected islands, cords, and strands within
the collagenized fibrous connective tissue stroma.
In higher magnification, the darkly staining periphery is
composed of tall columnar cells with hyperchromatic
The nucleus tends to be round/oval in shape, and the
nuclei of the adjacent cell are roughly in the same
location within the cytoplasm.
The nuclei are oriented away from the basement
membrane, with small clear vacuoles between the
nucleus and the basement membrane.
Composed of many small discrete islands of
tumor composed of peripheral layer of cuboidal or
Nuclei are generally well polarised.
The cells resemble ameloblasts or pre-
These enclose a central mass of polyhedral,
loosely arranged cells resembling the stellate
The ameloblast like cells are arranged in irregular
masses, or more frequently, as a network of
interconnected strands of cells.
Each of these strands is bound by a layer of tall
columnar cells, between these layers may be
found stellate reticulum like cells, these stellate
reticulum like tissue is less prominent in Plexiform
ameloblastoma than in the follicular
The cells occupying the position of the stellate
reticulum undergo squamous metaplasia.
Sometimes with keratin formation in the central
part of the tumor island.
There is marked transformation in the cytoplasm
if the cells.
The cytoplasm is very coarse, granular,
Basal cell type of ameloblastoma:
It resembles the basal cell carcinoma of the skin.
It is rarest histological subtype.
The epithelial cells are more primitive and less
columnar, and are arranged in sheet, no stellate
reticulum like cell are present in the center of the
Desmoplastic ameloblastoma :
Half of the Desmoplastic ameloblastoma are
located in the maxilla, and the vast majority occur
in the anterior or premolar portion of jaws.
This is in contrast to classical type of
ameloblastoma, which are found in the posterior
region of mandible.
Maxillary lesion are more insidious than
mandibular tumors owing to the proximity of vital
structures and maxillary sinus.
Also, the thin cortical bone of the maxilla forms a
weak barrier for the spread of the tumor.
Desmoplastic ameloblastoma :
Dense collagen stroma, may be hyalinised or
Has greater tendency to grow in thin strands and
cords of epithelium rather than island like pattern.
The epithelial component is almost compressed
and fragmented by the dense hyalinised stroma.
The peripheral cells are flattened or cuboidal
rather than tall columnar in appearance.
Central cells are often scanty.
Reverse polarity and subnuclear vacuolisations is
difficult to recognize.
Reichart et al.
Follicular type had the highest rate of recurrence,
while acanthomatous type has least rate of
Plexiform is intermediate
The type of T/t that have been used include
1. Radical excision.
2. Conservative surgical excision.
3. Curettage. ( least desirable – highest rate of
5. Radiation therapy.
6. Combination of surgery & radiation.
Text book of oral pathology- Shafer 5th edition.
Text book of oral & maxillofacial pathology-
Neville 3rd edition.
Color atlas of oral pathology- Goro Ishikawa
Manual of oral pathology- Dr. Anand