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– Locally aggressive, slow-growing, destructive lesion.
– Root resorption of adjacent teeth is common.
• Radiographic features
– Unilocular or multilocular expansile radiolucency with well-dened borders
and possible displacement of surrounding structures.
– May have “soap bubble” or “honeycombed” appearance with scalloping
borders.
• Histopathologic features
– Follicular pattern—most common. Islands of odontogenic epithelium with
palisaded columnar cells at the periphery.
– Plexiform pattern—second most common type. Odontogenic epithelial cells
proliferate in a network of connecting strands.
– Desmoplastic ameloblastoma—thickened bony trabeculae in a dense bro-
blastic collagenized stroma. Islands and cords of odontogenic epithelium.
– Basal cell pattern—least common type. Tumors in which the hyperchromatic
basaloid cells form islands and connecting strands in a brous stroma.
• Treatment and prognosis
– Bony resection with 1.0–1.5cm margins and anatomic barrier margins of one
uninvolved anatomic barrier. For both primary and recurrences.
– Enucleation and curettage will have a 70–85% recurrence rate in 5 years.
– Ameloblastomas treated by resection have a 98% cure rate.
R. N. Sharobiem et al.
Unicystic Ameloblastomas/Ameloblastomas Associated
withCysts (13%)
• Unicystic ameloblastoma is a term used to describe an ameloblastoma arising in
the lining, lumen, or wall of a cyst.
• Clinical features
– 90% occur in the mandible, especially posterior region.
– In situ and microinvasive lesions are normally discovered histopathologically
after removal of a dentigerous cyst.
• Radiographic features
– Well-dened, unilocular radiolucency extending from the crown of a tooth.
Has the typical appearance of a dentigerous cyst.
• Histopathologic features
– Similar features of ameloblastoma, but in situ, intraluminal, and mural com-
ponents are histological diagnoses depending on the relationship to the
cyst lining.
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• Treatment and prognosis
– Enucleation vs. resection depending on the invasiveness and size of tumor.
Peripheral Ameloblastoma (1%)
• Clinical features
– Firm and painless, single or polypoid exophytic mass arising from the gingiva
or alveolar mucosa. Normally non-ulcerated and may be sessile or
pedunculated.
– Most occur in posterior regions of the jaws and mandible more common than
maxilla.
• Radiographic features
– Does not invade bone, but may show saucerization of alveolar bone.
• Histopathologic features
– Similar to intraosseous form with follicular, plexiform, and basilar forms.
• Treatment and prognosis
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– Soft tissue mass excision with 2–3mm margins.
Malignant Ameloblastoma (MA) andAmeloblastic
Carcinoma (AC)
• Clinical features
– MA may metastasize to lymph nodes, long bones, vertebrae, etc. Lungs most
common. MA requires metastasis to be a diagnosis, as it is otherwise a benign
process.
– Metastasis is normally noticed 10 years after treatment of the primary
jaw tumor.
– AC may be locally aggressive and metastasize, as well.
– ACs are usually large masses with ulcerations, bone resorption, and tooth
mobility.
– AC behaves similar to SCC.
• Radiographic features
– MA will appear as a typical benign ameloblastoma, but with concomitant
metastasis.
– AC will normally have ill-dened margins and cortical destruction.
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• Histopathologic features
– MA is a benign ameloblastoma histopathologically, but with local or distant
metastasis. The lesions show no cellular atypia or pleomorphism.
– AC epithelial cells are atypical and consistent with a malignancy.
• Treatment and prognosis
– Treatment requires surgical resection with 2–3 cm margins and neck
dissection.
– Postoperative radiation therapy also must be considered.
– Prognosis is guarded with 5-year survival rates less than 40%.
– Distant metastasis is associated with poor prognosis, and palliative chemora-
diotherapy may be indicated.
– Recurrence rate >60%.
R. N. Sharobiem et al.
Clear Cell Odontogenic Carcinoma
• Clinical features
– Symptomatic central expansion of the jaws—mandible 84%.
– Expansion may displace teeth or resorb roots.
– Locally aggressive and may invade local soft tissues ~60% of cases.
– 20–25% will have metastasis, mostly to lymph nodes or lungs.
• Radiographic features
– Large, unilocular, expansile radiolucency. Can have dened or irregular
margins.
• Histopathologic features
– Negative staining for mucin unlike clear cells of the mucoepidermoid
carcinomas.
– Grows in a lobular pattern with a surrounding capsule.
– Demonstrate little pleomorphism, but are inltrative and have capsular
invasion.
• Treatment and prognosis
– Treatment is bony resection with a 1.5-cm margin including periosteum. Soft
tissue excision if there is invasion.
– Selective neck dissection if lymph nodes involved on CT scan or clinical sus-
picion from aggressive behavior such as pain, paresthesia, rapid growth, or
large size.
– Postoperative radiation therapy also must be considered for close/positive
margins.
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Adenomatoid Odontogenic Tumor/Cyst
• Clinical features
– Two-thirds tumor/cyst—two-third occur in maxilla, two-third occur in young
women (preteen and teenage years), two-third associated with unerupted
tooth, and two-third of those teeth are canines.
– Displaces rather than resorbs roots.
• Radiographic features
– Well-dened, radiolucency usually associated with an impacted tooth (follic-
ular type). May also appear as a unilocular radiolucency not related to an
unerupted tooth (extrafollicular type).
• Histopathologic features
– Grossly has a thick connective tissue capsule, which makes separation from
bone easy and an exophytic epithelial lining, sometimes lling the entire
lumen. Aspiration will return a straw-colored uid.
• Treatment and prognosis
– Enucleation and curettage are curative without recurrence.
– The associated tooth must be removed as it is entirely within the cystic lumen
and not surrounded by bone.
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Calcifying Epithelial Odontogenic Tumor
• Clinical features
– Described by Pindborg in 1956 and frequently termed a “Pindborg Tumor.”
– Asymptomatic expansion of the jaw—mandible two to three times more than
maxilla.
– Invasiveness varies from mild to moderate.
– Slow-growing, benign neoplasm.
• Radiographic features
– Early tumors are radiolucent, while larger more mature tumors are mixed
radiolucent-radiopaque. May be unilocular or multilocular with “soap bub-
ble” appearance. May have a distinct sclerotic border with surrounding bone
or an ill-dened border with no clear demarcation (20%). Margins often
scalloped.
– Most are associated with crown of an impacted tooth mostly mandibular
third molar.
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• Histopathologic features
– Inltrating and unencapsulated tumors.
– Epithelial components are sheets and islands of eosinophilic polygonal/poly-
hedral cells with intercellular bridges. Nuclei are central with prominent
nucleoli and may have pleomorphism.
• Treatment and prognosis
– Less aggressive and invasive than either the ameloblastoma or myxoma.
– Enucleation and curettage show recurrence rates of 15–30% after 2–4 years.
– Best treated with bony resection using 1.0–1.5 cm margins and one unin-
volved anatomic barrier (similar to ameloblastoma).
– Calcifying epithelial odontogenic tumor is curable with resection.
R. N. Sharobiem et al.
Squamous Odontogenic Tumor
• Clinical features
– Rare, hamartomatous proliferation.
– Painless expansion of alveolar process that may displace teeth or resorb roots.
Premolar-canine region of maxilla and molar region of mandible.
• Radiographic features
– Well-dened, unilocular radiolucencies less than 3.0cm and conned to alve-
olar bone.
– May appear as a triangular radiolucent defect lateral to the root or the roots
of teeth.
• Histopathologic features
– Islands of well-differentiated squamous epithelium without peripheral colum-
nar cells, which are benign in appearance. Vacuolation and formation of
microcysts may occur.
• Treatment and prognosis
– Enucleation and curettage are curative with no recurrence.
– 20% of patients will have new lesions, which form in a different location.
Odontogenic Carcinomas
• Clinical features
– Residual odontogenic epithelium may undergo genetic alterations resulting in
malignancy.
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– Pain and swelling are the most common complaints; paresthesias are
also likely.
• Radiographic features
– May appear as a typical dentigerous or odontogenic cyst. The radiolucency
may also show irregular demarcation and a ragged border to the adja-
cent bone.
• Histopathologic features
– Odontogenic cyst with an invasive carcinoma arising from the cystic lining.
The carcinoma is usually well-differentiated squamous in nature and invades
the surrounding tissue.
• Treatment and prognosis
– Same regional lymph node and distant metastatic potential as a mucosal SCC
and should be treated the same way.
– Radical resection with or without radiation or adjuvant chemotherapy.
Odontogenic Tumors: Mixed Tumors
Ameloblastic Fibroma
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• Clinical features
– Asymptomatic expansion of the jaws. Mandibular molar region is preferred
site (70%), but may occur anywhere.
– Behaves as either a hamartomatous proliferation or a true neoplasm.
– Thought of as aborted attempt at tooth formation, without the formation of
calcied structures.
• Radiographic features
– Unilocular or multilocular complete radiolucency with well-dened
borders.
• Histopathologic features
– Consists of both active epithelial and mesenchymal components without cal-
cied structures. Well circumscribed and encapsulated.
• Treatment and prognosis
– Enucleation and curettage are curative as it is noninvasive beyond its capsule,
but with recurrence rates reported from 0 to 18%.
– Resection is reasonable in extremely large lesions.
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Ameloblastic Fibro-Odontoma
• Clinical features
– Asymptomatic expansion of the jaws—mandibular molar region
most common.
• Radiographic features
– Well-dened, mixed radiolucent-radiopaque appearance with irregular calci-
cations denser than the surrounding bone and similar to teeth.
• Histopathologic features
– Grossly and macroscopically, it has components of an odontoma and amelo-
blastic broma, so it will have soft and hard tissues.
• Treatment and prognosis
– Enucleation and curettage are curative without recurrence.
Ameloblastic Fibrosarcoma
• Clinical features
– Most common malignant odontogenic tumor.
– Asymptomatic jaw expansion—80% of cases in mandible.
– Locally aggressive, inltrative similar to ameloblastoma or myxoma.
• Radiographic features
– Multilocular, ill-dened, radiolucent, expansile lesion, which is destructive.
• Histopathologic features
– Similar to ameloblastic broma, but with cellular atypia. The epithelial com-
ponent remains benign, but the mesenchymal component is malignant with
hypercellularity, pleomorphism, and mitoses.
• Treatment and prognosis
– Best treated with bony resection using 1.0–1.5 cm margins and one unin-
volved anatomic barrier (similar to ameloblastoma and myxoma).
– Radiation therapy is of little value to this tumor, but chemotherapy protocols
have been used for more aggressive tumors.
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Odontoameloblastoma
• Clinical features
– Posterior molar/ramus region most common in either jaw.
– These are two separate entities that are co-existing in the same space.
• Radiographic features
– Features of both ameloblastomas and odontomas. Mostly multilocular mixed
radiolucent-radiopaque lesions with complex odontomas.
• Histopathologic features
– Epithelial components are identical to those of ameloblastoma with either
plexiform or follicular pattern.
• Treatment and prognosis
– Treatment and prognosis are the same as for invasive ameloblastoma, which
are bony resection with 1.0- to 1.5-cm margins and one uninvolved anatomic
barrier.
Odontoma
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• Clinical features
– Hamartoma of aborted tooth formation with calcied structures.
– Compound odontoma—multiple small toothlike structures. Common anterior
to mental foramen.
– Complex odontoma—amorphous calcied mass. Common posterior to men-
tal foramen.
• Radiographic features
– Compound odontoma—gravel-like appearance with outline of miniature teeth.
– Complex odontoma—dense, amorphous irregularly shaped mass.
– Both are well dened with a radiolucent rim surrounding the radiopacities.
• Histopathologic features
– Composed of mature dental tissues including enamel, dentin, cementum, and
pulp arranged in toothlike arrangements (compound) or unstructured sheets
(complex).
• Treatment and prognosis
– Enucleation and curettage are curable without recurrence.
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R. N. Sharobiem et al.
Odontogenic Tumors—Odontogenic Ectomesenchyme
Central Odontogenic Fibroma
• Clinical features
– Extremely rare, painless expansion that may displace teeth or resorb roots.
– Maxillary lesions are anterior to rst molar, while mandibular lesions are
posterior.
• Radiographic features
– Unilocular or multilocular, radiolucency with well-dened borders, some-
times sclerotic. Root resorption is common and divergence may also be seen.
• Histopathologic features
– Pattern 1—simple type. Stellate broblasts in a delicate loose brous tissue,
with various amounts of collagen and some rests of odontogenic epithelium.
– Pattern 2—WHO type. Well-demarcated or encapsulated type with cellular
brous tissue and myxoid areas.
– Granular cell odontogenic broma—sheets of large granular cells with inter-
spersing round islands of odontogenic epithelium.
• Treatment and prognosis
– Enucleation and curettage are curative and recurrence unlikely.
Peripheral Odontogenic Fibroma
• Clinical features
– Firm, sessile, painless soft tissue mass of the gingiva.
– Emerges from the gingival crevice or periodontal membrane.
– Nondestructive and noninvasive.
• Radiographic features
– No radiographic ndings unless underlying alveolar surface erosion/
saucerization.
• Histopathologic features
– Similar to central counterpart (WHO type) with interwoven fascicles of cel-
lular brous tissue mixed with myxoid areas.
• Treatment and prognosis
– Local soft tissue excision with 1–2mm margins and base of the broma.
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– Recurrences are rare, especially if base of emergence is excised.
Granular Cell Odontogenic Tumor
• Clinical features
– Most are asymptomatic expansions of the premolar–molar regions.
• Radiographic features
– Well-dened radiolucency, which can be unilocular or multilocular.
• Histopathologic features
– Sheets of large eosinophilic granular mesenchymal cells with small nests,
cords, or islands of odontogenic epithelium.
• Treatment and prognosis
– Enucleation and curettage are curative without recurrence.
Odontogenic Myxoma
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• Clinical features
– Asymptomatic jaw expansion—evenly distributed in the mandible and
maxilla.
– Growth characteristics and clinical presentation similar to ameloblastoma.
– Benign neoplasm with inltrative growth.
– May see tooth displacement, root resorption, and displacement of IA nerve
canal and soft tissue involvement.
• Radiographic features
– Unilocular or multilocular radiolucency with “honeycombed” appearance and
rarely as a unilocular radiolucency. Margins are often irregular or scalloped.
– “Stepladder” or the “soap bubble” appearance. “Sunburst” appearance has
also been described.
• Histopathologic features
– Unencapsulated, inltrating, gelatinous tumors with sparse cells that are spin-
dle shaped, round, or stellate with long cytoplasmic processes.
• Treatment and prognosis
– Bony resection with 1.0- to 1.5-cm margins and one uninvolved anatomic bar-
rier is curative. Overall prognosis is good and metastasis does not occur.
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