Odontogenic tumors Asmaa 2024.pdf

Odontogenic Tumors University of Tripoli Dental Faculty Department of Oral Medicine, Oral Pathology and Oral & Maxillofacial Surgery Oral Pathology Unit 3rd Year Dental Students 2023\2024 Dr. Asmaa...

Odontogenic Tumors University of Tripoli Dental Faculty Department of Oral Medicine, Oral Pathology and Oral & Maxillofacial Surgery Oral Pathology Unit 3rd Year Dental Students 2023\2024 Dr. Asmaa Salem Shanab 2024  Odontogenic Tumors: Definition of Odontogenic Tumors: A group of neoplasm & tumors-like malformations (hamartomas) derived from epithelial and/or ectomesenchymal elements that are parts of the tooth forming-apparatus. Origin of Odontogenic Tumors: odontogenic tissues. WHO Classification of Odontogenic Tumors / 2005: I. Benign Odontogenic Tumors: A. Odontogenic epithelium with mature, fibrous stroma without odontogenic ectomesenchyme: ✓ Ameloblastoma, solid/multicystic type ✓ Ameloblastoma, extraosseous/peripheral type ✓ Ameloblastoma, desmoplastic type ✓ Ameloblastoma, unicystic type ✓ Squamous odontogenic tumor ✓ Calcifying epithelial odontogenic tumor ✓ Adenomatoid odontogenic tumor ✓ Keratinizing cystic odontogenic tumor B. Odontogenic epithelium with odontogenic ectomesenchyme, with or without hard tissue formation: ✓ Ameloblastic fibroma ✓ Ameloblastic fibro-odontoma ✓ Ameloblastic fibro-dentinoma ✓ Odontoma, complex type ✓ Odontoma, compound type ✓ Odontoameloblastoma ✓ Calcifying cystic odontogenic tumor ✓ Dentinogenic ghost cell tumor C. Mesenchyme and/or odontogenic ectomesenchyme with or without odontogenic epithelium: ✓ Odontogenic fibroma ✓ Odontogenic myxoma / myxofibroma ✓ Cementoblastoma II. Malignant Odontogenic Tumors: A. Odontogenic Carcinomas: ✓ Metastasizing (malignant) ameloblastoma ✓ Ameloblastic carcinoma –primary type ✓ Ameloblastic carcinoma –secondary type, intraosseous ✓ Ameloblastic carcinoma –secondary type, peripheral Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 1 of 18  ✓ Primary intraosseous squamous cell carcinoma –solid type ✓ Primary intraosseous squamous carcinoma derived from keratocystic odontogenic tumor ✓ Primary intraosseous squamous cell carcinoma derived from odontogenic cysts ✓ Clear cell odontogenic carcinoma ✓ Ghost cell odontogenic carcinoma B. Odontogenic Sarcomas: ✓ Ameloblastic fibrosarcoma ✓ Ameloblastic fibro-dentino and fibro-odontosarcoma WHO Classification of Odontogenic Tumors / 2017: I. Benign Odontogenic Tumors: A. Epithelial Origin: ✓ Ameloblastoma ✓ Ameloblastoma, unicystic type ✓ Ameloblastoma, extraosseous/ peripheral type ✓ Metastasizing (malignant) ameloblastoma ✓ Squamous odontogenic tumor ✓ Calcifying epithelial odontogenic tumor ✓ Adenomatoid odontogenic tumor B. Mixed (Epithelial-Mesenchymal) Origin: ✓ Ameloblastic fibroma ✓ Primordial odontogenic tumor ✓ Odontoma, complex type ✓ Odontoma, compound type ✓ Dentinogenic ghost cell tumor C. Mesenchymal Origin: ✓ Odontogenic fibroma ✓ Odontogenic myxoma/myxofibroma ✓ Cementoblastoma ✓ Cemento-ossifying fibroma II. Malignant Odontogenic Tumors: ✓ Ameloblastic carcinoma ✓ Primary intraosseous carcinoma, NOS ✓ Sclerosing odontogenic carcinoma ✓ Clear cell odontogenic carcinoma ✓ Ghost cell odontogenic carcinoma ✓ Odontogenic carcinosarcoma ✓ Odontogenic sarcomas Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 2 of 18  WHO Classification of Odontogenic Tumors & Cysts of The Jaws/ 2022: I. Odontogenic Tumors: Benign epithelial odontogenic tumors: ✓ Adenomatoid odontogenic tumor ✓ Squamous odontogenic tumor ✓ Calcifying epithelial odontogenic tumour ✓ Ameloblastoma, unicystic ✓ Ameloblastoma, extraosseous/peripheral ✓ Ameloblastoma, conventional ✓ Adenoid ameloblastoma ✓ Metastasizing ameloblastoma Benign mixed epithelial & mesenchymal odontogenic tumors: ✓ Odontoma ✓ Primordial odontogenic tumor ✓ Ameloblastic fibroma ✓ Dentinogenic ghost cell tumor Benign mesenchymal odontogenic tumors: ✓ Odontogenic fibroma ✓ Cementoblastoma ✓ Cemento-ossifying fibroma ✓ Odontogenic myxoma Malignant Odontogenic Tumors: ✓ Sclerosing odontogenic carcinoma ✓ Ameloblastic carcinoma ✓ Clear cell odontogenic carcinoma ✓ Ghost cell odontogenic carcinoma ✓ Primary intraosseous carcinoma, NOS ✓ Odontogenic carcinosarcoma ✓ Odontogenic sarcomas II. Cysts of The Jaws: ✓ Radicular cyst ✓ Inflammatory collateral cysts ✓ Surgical ciliated cyst ✓ Nasopalatine duct cyst ✓ Gingival cysts ✓ Dentigerous cyst ✓ Orthokeratinised odontogenic cyst ✓ Lateral periodontal cyst and botryoid odontogenic cyst ✓ Calcifying odontogenic cyst ✓ Glandular odontogenic cyst ✓ Odontogenic keratocyst Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 3 of 18  Epithelial Odontogenic Tumors: 1. Ameloblastoma: ✓ It is a benign epithelial odontogenic tumor. ✓ It is rare & only accounts for about 1% of all oral tumors, where it accounts for up to 11% of odontogenic tumors. ✓ It is second most common tumor of the odontogenic tissues after odontomas. Origin: several origins have been suggested. 1) Odontogenic epithelium: a) Dental lamina + its remnants (Epithelial Rests of Serres). b) Enamel organ + its remnants (Reduced Enamel Epithelium). c) Epithelial root sheath of Hertwig’s + its remnants (Epithelial Rests of Malassez). 2) Epithelial lining of odontogenic cysts especially dentigerous cyst. 3) Basal cell layer of the oral epithelium. Clinico-Radiographic Situations: Ameloblastomas occur in 3 different clinico- radiographic situations requiring different therapeutic considerations & prognosis. 1) Conventional solid / multicystic intraosscous ameloblastoma (86% of all cases). 2) Unicystic ameloblastoma (13 % of all cases). 3) Peripheral (extraosseous) ameloblastoma (1 % of all cases). Conventional Solid / Multicystic Intraosscous Ameloblastoma: Definition: It is a benign but locally invasive neoplasm derived from remnants of odontogenic epithelium lying in a fibrous stroma. It has ↑↑ recurrence rate than other types of ameloblastoma. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 4 of 18  Clinical Features: ✓ Age incidence: 4th -5th decade. ✓ Sex incidence: male = female. ✓ Race incidence: ↑↑ in African. ✓ Site predilection: o Mandible > maxilla. o In mandible 70% in molar-ramus area (the commonest site), 20% in premolar area & 10% in incisor region. ✓ Signs & Symptoms: o Slowly growing bony swelling with locally invasive behavior. o In early stage may be asymptomatic & discovered during routine x-ray. o Later it may produce gradual facial asymmetry & thinning of the cortical bone resulting in an egg-shell crackling. o Pain & paresthesia may occur if the lesion is pressing upon a nerve or secondarily infected. o Displacement & looseness of involved teeth. o If it is left untreated for many years carcinoma can be seen. Radiographic Features: ✓ Multi-locular radiolucency: o Soap bubble: when loculations are large. o Honey combed: when loculations are small. ✓ Uni-locular radiolucecy; resembling cystic lesion with irregular scalloping margins. ✓ Root resorption & tooth displacement. ✓ May be associated with un-erupted tooth especially lower wisdom. Histopathological Features: ✓ Conventional ameloblastoma has 2 main microscopic patterns (depending on the arrangement of epithelium): o Follicular Ameloblastoma. o Plexiform Ameloblastoma. ✓ In some tumors both patterns coexist with no difference in the clinical behavior between various types. ✓ Less common histological variants of ameloblastoma include: o Acanthomatous Ameloblastoma. o Granular Cell Ameloblastoma. o Basaloid Ameloblastoma. o Desmoplastic Ameloblastoma. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 5 of 18  1. Follicular Ameloblastoma: ✓ The most common pattern. ✓ The odontogenic epithelium is arranged into follicles or islands resembling enamel organ, each follicle consists of 2 types of cells: (Ameloblast–like cells of an enamel organ) peripheral single layer of tall columnar cells with reversed polarity i.e. the nuclei of the cells located at the opposite pole of the basement A. Soild follicular ameloblastoma membrane. B. Microcystic follicular ameloblastoma C. Macrocystic follicular ameloblastoma (Stellate reticulum–like cells of an enamel organ) central core of loosely arranged angular or star shaped cells. ✓ The lesion is supported by a mature fibrovascular C.T. stroma. ✓ Central cystic formation is common due to degeneration in central cells within the follicle resulting microcystic spaces & macrocystic spaces with flattening of ameloblast-like cells. 2. Plexiform Ameloblastoma: ✓ The odontogenic epithelium is arranged in a network of anastomosing strands & cords with the same layers as follicular ameloblastoma (ameloblast-like cells & stellate reticulum-like cells). ✓ The supporting stroma tends to be loosely arranged & vascular. ✓ Cystic formation is due to degeneration in C.T. stroma rather than cystic change within the epithelium as follicular pattern. ✓ Then, dilated blood vessels are left without any support. They become enlarged & rupture leading to escape of blood into stromal spaces. These cases are known as heamango-ameloblastoma. 1) Soild plexiform ameloblastoma 2) Haemango-ameloblastoma 3. Granular Cell Ameloblastoma: changing stellate reticulum-like cells to granular cells that may be cuboidal or rounded cells in shape with their nuclei pushed to the cell wall & their cytoplasm filled with eosinophilic granules. Electron microscopic study shows that the granules represent lysosomes. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 6 of 18  4. Acanthomatous Ameloblastoma: stellate reticulum-like cells undergo squamous metaplasia which produces keratin in form of keratin pearls. It may be confused with squamous cell carcinoma or squamous odontogenic tumor. 5. Basaloid Ameloblastoma: stellate reticulum-like cells change to nests of hyperchromatic basaloid cells. This type of ameloblastoma shows close similarity to basal cell carcinoma. 6. Desmoplastic Ameloblastoma: showing compressed follicles due to deposition of large amount of collagen fibers in C.T. stroma leading to bizarre-like shape. Hyalinized C.T. stroma: the stroma undergo hyalinization to Note involve a zone of about (30 microns) immediately adjacent to epithelial follicle. This zone is due hyaline degeneration of collagen fibers & never calcify i.e. remain eosinophilic. Treatment: ✓ The conventional ameloblastoma tends to infiltrate between intact cancellous bone trabeculae at the periphery of the tumor. The margin of the tumor often extends beyond its radiographic or clinical margins, therefore with curettage; recurrence rate is 50% to 90%. ✓ Marginal resection at least 1cm past the margins reduces the recurrence to 15%. Unicystic Ameloblastoma: Definition: Locally invasive tumor consists of a central large cystic cavity, which is less aggressive than conventional ameloblastoma. Origin: De- novo as a neoplasm. Neoplastic transformation of a pre-existing odontogenic cyst (dentigerous cyst). Clinical Features: Age incidence: common in younger patients (average age 23 years). Sex incidence: male = female. Site predilection: o Mandible >maxilla. o 90% occurs in lower posterior area with unerupted lower wisdoms. Symptom & signs: o Asymptomatic, large lesions may cause painless, slowly growing swelling. o Associated with impacted 3rd molar. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 7 of 18  Radiographic Features: It appears as well-defined unilocular radiolucency that surround the crown of unerupted third molar and resembling dentigerous cyst. Histopathological Features: There are 3 histopathological variants of unicystic ameloblastoma. 1. Luminal Ameloblastoma: The tumor tissue is confined to the luminal surface of the cyst (the lining). The lesion consists of a fibrous cyst wall with a lining that consists totally or partially of ameloblastic epithelium which showing: o Basal layer is ameloblast-like cells with reverse polarity, hyperchromatic nuclei and vacuolated cytoplasm. o The overlying epithelial cells are loosely cohesive and resemble stellate reticulum cells. 2. Intra-luminal Ameloblastoma: one or more nodules of ameloblastoma project from the cystic lining into the lumen of the cyst. Lesions show plexiform pattern called plexiform unicystic ameloblastoma. 3. Mural Ameloblastoma: the fibrous wall of the cyst is infiltrated by follicular or plexiform ameloblastoma. Treatment: usually treated as cysts by enucleation (without safety margin) with recurrence rate 10-20%. Mural variant should be treated aggressively like conventional amelobastomas. Peripheral (Extraosseous) Ameloblastoma: Definition: ❖ A benign odontogenic epithelial tumor confined to the soft tissues overlying the tooth bearing area. ❖ Uncommon form (1%). Origin: ❖ Basal cell layer of oral mucosa. ❖ Odontogenic epithelial remnants of dental lamina in oral mucosa. Clinical Features: ✓ Age incidence: middle-aged patients. ✓ Site predilection: posterior gingival & alveolar mucosa. Mandible > maxillae. ✓ Symptom & signs: painless non-ulcerated sessile or pedunculated gingival or alveolar mucosal lesion. Histopathological Feature: as conventional pattern. Treatment: surgical excision is treatment of choice with recurrence rate 25%. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 8 of 18  2. Adenomatoid Odontogenic Tumor (AOT): Definition: ✓ It is benign epithelial odontogenic tumor, characterized by duct-like structure & variable degrees of inductive change in C.T. stroma. ✓ It is generally believed that the lesion is not a neoplasm hamartoma in nature. Origin: a) Enamel organ epithelium. b) Remnants of dental lamina. Clinical Features: ✓ Age incidence: 2nd decade of life. ✓ Sex incidence: female > male. ✓ Site predilection: o Maxilla > mandible (2:1). o Most common in canine region. ✓ Symptom & signs: o Asymptomatic discovered by chance on X-ray. o Slowly growing small lesion (seldom exceed 3 cm in diameter), larger lesions cause a painless expansion of the bone. o Rarely, it occurs as sessile masses on the facial gingiva of the maxilla. o Associated with impacted tooth especially upper canine. AOT Variants: ✓ Central (intraosseous): a) Follicular type: (73%) associated with crown of an unerupted tooth. b) Extrafollicular type: (24%) not related to an unerupted tooth. ✓ Peripheral (extraosseous): rare (3%) it is situated in gingiva. Radiographic appearance of AOT variants: F=Follicular. E=Extrafollicular sites. Radiographic Features: P=Peripheral. ✓ Follicular type well defined unilocular radiolucency involves the crown of unerupted tooth (usually canine). The radiolucency extends apically along the root past the cemento-enamel junction D/D dentigerous cyst. ✓ Extrafollicular type well defined unilocular radiolucency usually located between the roots of erupted teeth. ✓ Often, it contains faint (snowflakes) calcifications patchy radiopacities. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 9 of 18  Histopathological Features: ✓ The tumor may be solid or cystic. ✓ It is made of spindle shaped epithelial cells that form sheets, islands and whorled masses of cells in a little fibrous C.T. stroma. ✓ Rings of columnar epithelial cells give rise to: a) Tubular structure two rows of cells with eosinophilic homogenous material in between the two rows. b) Convoluted bands two rows of cells with eosinophilic material in between the two rows & with a shape of convoluted tubules. c) Duct-like structures consist of a central space surrounded by single layer of columnar cells (their nuclei are situated basally away from central space). The central space contains a homogenous eosinophilic material forming a thin layer in contact with the cells. The eosinophilic material is thought to be a basement membrane-like material since it is PAS positive. ✓ Small foci of calcifications can be seen, represent dentine, enamel or cementum. ✓ The tumor is well encapsulated (thick fibrous capsule). Adenomatoid odontogenic tumor: A. Fibrous CT capsule. B. Lobules of polyhedral-shaped epithelial cells. C. Sheets of spindle-shaped epithelial cells. D. Duct-like structure of columnar epithelial cells with eosinophilic band. E. Convoluted tubules of columnar epithelial cells. F. Areas of calcification. Treatment: this tumor is capsulated so it is treated with simple enucleation. Prognosis: good prognosis (benign tumor & no rate of recurrence as it is capsulated). 3. Calcifying Epithelial Odontogenic Tumor (CEOT / Pindborg’s Tumor): Definition:  It is a benign but locally invasive epithelial neoplasm characterized by development of intra-epithelial amyloid-like material which may become calcified & liberated into surrounding stroma.  Uncommon epithelial lesion that accounts for < 1% of all odontogenic tumors. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 10 of 18  Origin:  Stratum intermedium of the enamel organ or Reduced Enamel Epithelium.  Dental lamina + its remnants (Epithelial Rests of Serres). Clinical Features:  Age incidence: average age 40 years.  Sex incidence: no sex predilection.  Site predilection: ▪ Central (intra-osseous) mandible > maxilla. In mandible, the most common site is molar -premolar region. Half the cases are associated with the crown of unerupted tooth. ▪ Peripheral (extra-osseous) anterior region.  Symptom & signs: ▪ Painless slowly growing swelling & may be associated with impacted tooth. ▪ Peripheral tumor appears as sessile mass on the anterior gingiva. Radiographic Features:  Ill-defined irregulr unilocular or multilocular radiolucency containing radio-opaque masses (calcific deposits) of varying size and opacity & located close to crown of unerupted tooth giving rise to the term ‘driven snow appearance’. Histopathological Features:  Proliferated odontogenic epithelial cells in the form of islands, strands & sheets.  The epithelial cells are large polyhedral with well-defined borders, giant nuclei, nuclear pleomorphism & prominent inter-cellular bridges (but it doesn’t indicate malignancy).  Amyloid-like material pools of homogeneous eosinophilic material seen between the epithelial cells. This homogenous A=Sheets of polyhedral cells. material can be stained with thioflavin T & B=Amyloid-like material. Congo red. C=Liesegang ring calcification.  Liesegang ring calcification amyloid-like material may undergo calcification in the form of concentric laminated blue ring.  A fibrovascular C.T. stroma supported the lesion.  The tumor is not capsulated. Treatment:  It has limited invasive potential (less aggressive than ameloblastoma) therefore local excision with narrow margin is indicted. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 11 of 18  Mixed (Epithelial & Ectomesenchymal) Odontogenic Tumors: 1. Ameloblastic Fibroma: Definition: ✓ Rare benign mixed odontogenic tumor in which both the epithelium & ectomesenchymal tissues are neoplastic. Origin: dental papilla, dental follicle or periodontal ligament. Clinical Features: ✓ Age incidence: 1st & 2nd decades. ✓ Sex incidence: male > female. ✓ Site predilection: mandibular premolar-molar area. ✓ Symptom & signs: painless, slowly growing swelling. Radiographic Features: ✓ Well defined unilocular (mainly) or multilocular radiolucent area. ✓ May be surrounded by sclerotic border. ✓ It is often associated with unerupted tooth. Histopathological Features: ✓ The tumor is macroscopically is well circumscribed & may or not be encapsulated. ✓ Highly cellular mesenchymal tissue resembling the primitive dental papilla, mixed with proliferated odontogenic epithelium. ✓ The epithelim components: Show one of two patterns: Long anastomosing cords, strands, usually only two cells in thickness, composed of cuboidal or columnar cells. Small discrete islands resembling enamel organ (peripheral columnar cells with reverse polarity resembling ameloblasts surround a central mass of loosely arranged star-shaped cells resembling Ameloblastic fibroma: stellate reticulum). A=Odontogenic epithelial rosette. ✓ The mesenchymal components: B= Odontogenic epithelial nest. ↑↑ cellular than C.T. of ameloblastoma. C= Odontogenic epithelial finger-like strand. D= Primitive odontogenic mesenchyme. It consists of plump stellate & ovoid cells in a loose matrix resemble the immature dental papilla with little collagen fibers. Juxta-epithelial hyalinization (cell-free zone) around epithelial islands. ✓ If the lesion contains dentine called Ameloblastic Fibro-dentinoma. ✓ If it contains enamel & dentine called Ameloblastic Fibro-odontoma. Treatment: ✓ Conservative local excision is the treatment of choice with 20% recurrence rate. ✓ It recurs in the form of ameloblastic fibrosarcoma. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 12 of 18  N.B. ❖ Ameloblastic Fibro-dentinoma: it is very rare mixed neoplasm composed of odontogenic epithelium & immature C.T. and characterized by formation of dysplastic dentine (dentinoid). ❖ Ameloblastic Fibro-odontoma: it is rare mixed neoplasm composed of proliferating odontogenic epithelium & ectomesenchymal tissue and varying degrees of dental hard tissue formation consists of dentine-like material & enamel-like material (enameloid). 2. Calcifying Odontogenic Cyst COC / (Gorlin’s Cyst): Definition: ✓ A benign mixed odontogenic cystic lesion, with solid variants (ghost cell tumor & ghost cell carcinoma). Clinical Features: Age incidence: 2nd & 3rd decades. Site predilection: most commonly anterior maxilla (canine region). Central / peripheral types. May be associated with odontomas. Radiographic Features: Well-defined unilocular or multilocular radiolucency, contain radio-opaque masses. May be associated with unerupted tooth (most commonly canine). Histopathological Features: Well-defined cystic lesion with a fibrous capsule & a lining of odontogenic epithelium of 4-10 cells in thickness shows. o Basal layer of cuboidal or columnar cells (ameloblast-like cells). o The overlying layer of loosely arranged cells (stellate reticulum-like cells). The most characteristic histopathologic feature of COC is the presence of variable numbers of ghost cells within the epithelial component. Ghost cells are eosinophilic, swollen altered epithelial cells characterized by loss of their nuclei with preservation of the basic cell outline. They may undergo calcification. Calcification is seen as dentinoid (dentine-like irregular eosinophilic masses) or dystrophic calcification. All these structures can invade the cyst lumen & C.T. capsule in addition to foreign body giant cells in C.T. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 13 of 18  3. Odontoma: Definition: ✓ A non-neoplastic developmental malformation (hamartomas) that contains fully formed enamel, dentine, cementum & pulp. ✓ Most common type of odontogenic tumors. Etiology: Unknown origin. Local trauma or infection. Genetic (inherited or mutation). ✓ Both the epithelial & mesenchymal cells exhibit complete differentiation results in formation of functional ameloblasts & odontoblasts form enamel & dentine. ✓ These are laid down in an abnormal pattern due to failure of cells to reach the morpho-differentiation stage. Types Of Odontomas: 1. Compound odontoma: o A malformation in which all dental tissues represented in more orderly pattern than in the complex odontoma. o Composed of multiple small tooth-like structures. 2. Complex odontoma: Compound odontoma o A malformation in which all dental tissues represented in more disorderly pattern than in compound odontoma. o Composed of a single mass of hard & soft dental tissues showing no anatomic resemblance to a tooth. Clinical Features: ✓ Age incidence: children & young adults. ✓ Sex incidence: male > female. ✓ Site predilection: o Maxilla > mandible. Complex odontoma o The compound type most commonly in anterior maxilla. o Complex type most commonly in posterior mandible. ✓ Symptom & signs: o Most odontomas are asymptomatic. o Large lesion cause expansion of the jaw. o Odontoma may prevent eruption of a permanent tooth. o Compound odontomas are more frequently diagnosed than complex. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 14 of 18  Radiographic Features: ✓ Compound odontoma appears as collection of tooth-like structures of varying size & shape (a bag of teeth) surrounded by a narrow radiolucent zone. ✓ Complex odontoma appears as a calcified mass with the radiodensity of tooth structure which is also surrounded by a narrow radiolucent rim. Histopathological Features: ✓ Compound odontoma consist of multiple denticles embedded in fibrous tissue. The denticles are made of regular enamel, dentine, cementum & pulp arranged as in normal teeth. ✓ Complex odontoma consist of a conglomerate mass of haphazardly (irregular) arranged but well-formed enamel, dentine, cementum & pulp. ✓ Lesions are surrounded by fibrous capsule. Compound odontoma Complex odontoma Treatment: ✓ Odontomas are treated by simple local excision with excellent prognosis. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 15 of 18  Ectomesenechymal Odontogenic Tumors: 1. Odontogenic Fibroma: Definition: ✓ A benign, fibroblastic neoplasm containing varying amount of inactive odontogenic epithelium. Origin: ▪ Periodontal ligament. ▪ Dental papilla. ▪ Dental follicles. Clinical types: ▪ Central odontogenic fibroma. ▪ Peripheral odontogenic fibroma. Clinical Features: ✓ Age incidence: 40 years. ✓ Sex incidence: female > male. ✓ Site predilection: commonly in anterior maxilla. ✓ Symptom & signs: ▪ Small lesion usually asymptomatic. ▪ The larger lesion associated with localized bony expansion or with the loosening of adjacent teeth. Radiographic Features: it appears as well-defined unilocular radiolucency. Histopathological Features: ✓ It composed of: ▪ Cellular fibrous tissue containing strands & islands of inactive odontogenic epithelium. ▪ Calcifications composed of osteoid or cement-like tissues & dysplastic dentine may be present. ▪ Stellate fibroblasts & immature collagen resembling dental papilla. Central odontogenic fibroma has a loose ✓ The tumor is encapsulated. stroma with fine collagen fibrils and small odontogenic epithelial rests. Histological variants of odontogenic fibroma: 1) Simple (epithelial-poor type): the lesion is composed of mature fibrous tissues containing few epithelial rests. 2) WHO (epithelial-rich type): mature C.T. contains an abundant of epithelial rests. Treatment: enculation & curettage. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 16 of 18  2. Odontogenic Myxoma: Definition: ✓ A benign, but locally invasive neoplasm consisted of stellate cells in abundant mucoid stroma resembling developing dental follicle in both location & structure. Origin: ▪ Dental papilla. ▪ Dental follicles. ▪ Periodontal ligament. Clinical Features: ✓ Age incidence: Adults (median age= 30 years). ✓ Sex incidence: no sex predilection. ✓ Site predilection: ▪ Only in jaws bones; mandible > maxilla (premolar-molar). ▪ In place of missing or unerupted tooth. ✓ Symptom & signs: ▪ It is associated with missing or unerupted teeth. ▪ Bony hard fusiform swelling, sometimes large enough to produce facial deformity. ▪ Teeth may be displaced and loosened. ▪ Although benign, these tumors are locally destructive & aggressive and may extend into the nasopharynx, nose, paranasal sinuses or the orbit. ▪ High recurrence rate (why?) a) Non-encapsulated. b) Its content resembles a gelatine substance so it is very difficult to be controlled during surgery. Radiographic Features: ✓ Typically appears as multilocular radiolucent area with scalloped margin & soap bubble appearance. Resorption of related roots. Histopathological Features: ✓ The lesion is non-encapsulated, with infiltrative pattern of growth. ✓ Stellate/ spindle shaped cells with long anastomosing processes in abundant loose mucoid stroma. ✓ Islands of inactive epithelial cells are usually present. ✓ Little amount of collagen is present in the stroma if prominent the tumor may be called fibromyxoma / myxofibroma. Treatment: ✓ It is treated by resection; as it recurs due to lack of encapsulation and loose gelatinous nature of the tumor infiltrating bone trabeculea. Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 17 of 18  3. Cementoblastoma (True Cementoma): Definition: A rare benign ectomesenchymal odontogenic tumor of cementoblast origin, related to a vital tooth. Origin: periodontal ligament & cementoblast. Clinical Features: Age incidence: average age is 25 years. Sex incidence: male > female. Site predilection: mandible > maxilla (especially lower first permanent molar). Symptom & signs: o It forms an irregular or rounded mass attached to the apical ⅓ of the roots. o Slow growing with bony expansion. o Pain is diagnostic feature, usually of low grade intermittent pain and become more intense when the area is palpated. o The associated tooth is vital. Radiographic Features: Typically appears as well-demarcated radiopaque mass with thin radiolucent rim attached (fused) to the root of the lower tooth. Resorption of the related root is common. Histopathological Features: It consists of sheets and thick trabeculae of mineralized material (cementum or cementum-like tissue) with prominent basophilic reversal lines and cells lying in lacunae. The mineralized trabeculae are usually lined by prominent cementoblast cells. Cellular fibrovascular tissue is present between the mineralized trabeculae. The periphery of the lesion is composed of uncalcified matrix. Multinucleated cementoclast are seen. Treatment: Excision with extraction of the associated tooth. Recurrence is not seen good prognosis. N.B ❖ Malignant Ameloblastoma: this term is used for a tumor that shows the. histopathologic features of ameloblastoma without any cytologic features of malignancy both in the primary tumor and in the metastatic deposits. ❖ Ameloblastic Carcinoma: this term is used for a tumor that shows the histopathologic features of ameloblastoma in addition to cytologic features of malignancy both in the primary tumor and in the metastatic deposits. These include an increased nuclear/ cytoplasmic ratio, hyperchromatism & pleomorphism & abnormal mitosis. ☺Thank you☺☺ Odontogenic Tumors by/Dr. Asmaa Shanab (2024) Page 18 of 18