19 Odontogenic cysts and tumors

Question 1

Classify the odontogenic ectodermal tumors.

Answer 1

Ectodermal - Ameloblastoma, Calcifying Epithelial Odontogenic Tumor (Pindborg Tumor or CEOT), Adenomatoid Odontogenic Tumor (AOT), Squamous Odontogenic Tumor (SOT)

Question 2

Classify the odontogenic mesodermal tumors.

Answer 2

Mesodermal - Central Odontogenic Fibroma, Peripheral Odontogenic Fibroma, “Odontogenic” Myxoma, Cementum Lesions (Central cemento-ossifying fibroma & Benign cementoblastoma “true cementoma” & Gigantiform cementoma)

Question 3

Classify the odontogenic mixed (epithelial and connective tissue) tumors.

Answer 3

Mixed - Ameloblastic fibroma, Ameloblastic fibro-odontoma, Odontoma

Question 4

Describe the characteristics, typical age and location, radiographic and histologic findings, treatment and variants of: Ameloblastoma

Answer 4

Most painless, all ages, more so in middle ages, can have cortical expansion, always radiolucent, epithelial islands and cords where peripheral cells show palisading (columnar) and reverse nuclearpolarity. Tx: surgical curretage (50% recur). Variants: Peripheral, Unicystic, Malignant ameloblastoma “benign but metastasizes”, Ameloblastic carcinoma.

Question 5

Calcifying epithelia lodontogenic tumor

Answer 5

All ages, more common in mandible, “driven snow” lucency to mixed lucent/opaque, often associated with unerupted teeth. Islands and sheets of pleomorphic epithelial cells. Tumor produces protein matrix similar to enamel matrix, Tx: surgical.

Question 6

Adenomatoid odontogenic tumor

Answer 6

Common in teens, in maxilla, females, 3/4 anterior jaw and unerupted teeth asymptomatic. Radiolucent (pericoronal), may have flecks of opacity. Encapsulated swirls of epithelial cells containing rosettes or duct-like spaces lined by cuboidal or columnar cells. Tx: Enucleation

Question 7

Squamous odontogenic tumor

Answer 7

Radiolucency around tooth roots. Islands of well-differentiated squamous epithelium. Peripheral layer of calls flattened. Tx: Curettage

Question 8

Describe the characteristics, typical age and location, radiographic and histologic findings, treatment and variants of: Central odontogenic fibroma

Answer 8

Benign, radiolucent to mixed lucent/opaque. 2 types: 1. Simple - delicate fibrillar stroma of collagen containing fibroblasts. 2. WHO type - stroma collagenous but may be more mature, variable amounts of odontogenic epithelium and calcifications. Tx: surgical removal

Question 9

Peripheral odontogenic fibroma

Answer 9

Reactive gingival lesion of PDL origin, more common in young people and in the anterior gingiva. Cellular fibrous connective tissue with calcifications, bone, cementum, dystrophic.

Question 10

Odontogenic myxoma

Answer 10

All ages, more common in young, asymptomatic, with or without expansion. Radiolucency often containing residual opaque trabeculae. Hypocellular tumor, scattered plump fibroblastic cells. Delicate collagen fibrils and abundant ground substance (glycosaminoglycans “GAGS”). Histology: often mistaken for normal anatomic structures (dental papilla or follicle). Tx: Block resection

Question 11

Cementum lesions

Answer 11

Inlcude 1. Central cemento-ossifying fibroma, Benign cementoblastoma, Gigantiform cementoma

Question 12

Central cement-ossifying fibroma

Answer 12

Neoplasm of PDL origin. Adults, more commin in mandible, females, and blacks. Asymptomatic with or withour expansion. Well circumscribed, associated with tooth roots, completely lucent to mixed lucent/opaque to mostly opaque. Very cellular fibroblastic stroma, containing trabeculae of bone with cellular inclusions or “globules” of acellular cementum or both. Usually encapsulated. Tx: Enucleation

Question 13

Benign cementoblastoma

Answer 13

“True Cementoma” - 2-4 decades, more commin in mandibular first molar, PAIN, may have expansion, tooth vital vs condensing osteitis - non vital. Radiographic 1. sclerotic mass with peripheral radiolucent zone 2. Fused with tooth root 3. Radiopaque center. Sclerotic trabeculae of cementum with variable amounts of “active” fibroblastic stroma with giant cells. Peripheral trabeculae characteristically at right angles to surface. Fused to tooth root. Tx: Surgival removal, low recurrence

Question 14

Gigantiform cementoma

Answer 14

Must be autosomal dominant, Radiographic - multiquadrant globular opacities. Globular sclerotic masses of cementum, histology not diagnostic. Tx: Usually none

Question 15

Describe the characteristics, typical age and location, radiographic and histologic findings, treatment and variants of: Ameloblastic fibroma

Answer 15

Young 1-3 decades, more commin in posterior mandible, asymptomatic. ALWAYS radiolucent. Long strands or cords of epithelial cells resembling dental lamina in a highly cellular connective tissue of fibroblasts and delicate collagen fibrils. Tx: surgical removal. Variant: ameloblastic fibrosarcoma - rare malignant transformation of mesenchymal component

Question 16

Ameloblastic fibro-odontoma

Answer 16

Young 1-3 decades, asymptomatic. Mixed lucent/opaque overlying unerupted tooth. Some areas like ameloblastic fibroma. Other areas products of ontogenesis. In functional areas, morphology recapitulates normal ondontogensis in that epithelial component “opens up” like enamel organ with central stellate reticulum and peripheral cells showing palisading and reverse nuclear polarity. Not-neoplastic. Tx: Surgical removal

Question 17

Odontoma

Answer 17

**Most common odontogenic tumor. Epithelial and mesenchymal cells functional and produce products of odontogenesis. Viewed as a developmental hamartoma, not a neoplasm. Young 1-3 decades, asymptomatic. Radiopaque with thin lucent border (follicle) often overlying unerupted teeth. Comound - tooth like more common in anterior jaws. Complex - random deposition - more common in poster jaws. Early lesions more active like ameloblastic fibro-odontoma. Late lesions with more mature enamel, dentin, cementum and pulp. Tx: Surgical removal. Complications - dentigerous cyst, ameloblastom.