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Ameloblastoma
Ameloblastoma is a true neoplasm originating from the enamel organ, classified by clinical and histological types, with a notable prevalence in the mandible and a mean diagnosis age of 30-39 years. The tumor displays varying growth patterns and can have high recurrence rates, with management strategies ranging from enucleation to more aggressive surgical interventions. Malignant variants, including ameloblastic carcinoma, present significant challenges due to their aggressive nature and potential for metastasis, primarily to the lungs and cervical lymph nodes.
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Ameloblastoma is a benign neoplasm of dental origin, previously known as adamantinoma, characterized by non-differentiated enamel organ-like tissues.
Ameloblastoma arises from dental organ remnants and is classified into solid/multicystic, unicystic, and peripheral types based on behavior, location, and histology.
Typically seen in individuals aged 10-90, with an average age of 30-39. Characterized by slow growth and potential for bone erosion, often occurs in the mandible.
Desmoplastic ameloblastoma resembles a mixed lesion, while differential diagnoses include odontogenic keratocyst, myxoma, and radicular cyst.
Common histological variations include plexiform, acanthomatous, granular, desmoplastic, and basal cell patterns, each with distinct characteristics.
Represents 10%-46% of intraosseous cases. Asymptomatic in younger patients, often resembling dentigerous cysts radiographically.
Occurs in 1%-10% of cases, primarily affects middle-aged individuals. Histopathologically similar to intraosseous forms with varying recurrence rates.
Poor prognosis for malignant cases, with metastases primarily affecting lungs and cervical lymph nodes. Histopathological features indicate malignancy.
Key references include textbooks on oral pathology and relevant online resources.
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Ameloblastoma
- 1.
- 2. INTRODUCTION Is atrue neoplasm of enamel organ type tissue which does not undergo differentiation to point of enamel formation Robinson described tumor as usually unicentric, nonfunctional, intermittent in growth, anatomically benign and clinically persistent.
- 3. Previously calledadamantinoma – malassez in 1885 Since this term implied the formation of hard tissue, and no such material was present in this lesion, it was replaced with term ameloblastoma suggested by churchill in 1934
- 4. ORIGIN Cell restsof dental organ, either remnants of dental lamina or remnants of hertwig’s sheath Epithelium of odontogenic cysts (dentigerous cysts and odontoma) Enamel organ Basal cell of surface epithelium of jaws Heterotopic epithelium of pituitary gland Reduced enamel epithelium
- 5. PATHOGENESIS • Low proliferationrate (ki67) • Over expression of antiapoptotic proteins (bcl-2, bclxl) Cell cycle related factors • Overexpression of interface protein (fibrinoge growth factor) • Overexpression of matrix metallo groth factor proteinase) Interface factors
- 6. CLASSIFICATION Based onclinical types 1. Conventional solid or multicystic (about 86% of all cases) 2. Unicystic (about 13% of all cases) 3. Peripheral (extraosseous) (about 1% of all cases)
- 7. Based onclinical behaviour Benign 1.solid/multicystic 2.unicystic 3.peripheral malignant 1.malignant ameloblastoma 2.ameloblastic carcinoma
- 8. Based onloaction Intraosseous/ central Extraosseous/ peripheral
- 9. Based onhistological classification 1.Follicular pattern and its variant granular acanthomatous basal cell variant 2. plexiform pattern 3. unicystic ameloblastoma luminal intraluminal mucosal
- 10. CONVENTIONAL SOLID ORMULTICYSTIC INTRAOSSEOUS AMELOBLASTOMA CLINICAL FEATURES • Age- 10-90 years • Average age of diagnosis 30-39 years • No sex predilection • Race: more common in blacks than in white race. • Site- Mandible (molar-angle-ramus area three times more commonly than premolar and anterior region combined)
- 11. CLINICAL PRESENTATION Slowgrowing, painless, bony hard swelling Facial asymmetry Large lesions- mobile teeth, pain and paraesthesia Locally invasive Infiltrate medullary spaces causing erosion of cortical bone
- 12. RADIOGRAPHIC FEATURES multilocularradiolucent lesion “soap bubble” appearance (when the radiolucent loculations are large) or as being “honeycombed”(when the loculations are small) Compartmented appearrances with septa of bone extending into radiolucent tumor mass Buccal and lingual cortical expansion Resorption of the roots of teeth adjacent to the tumor is common The margins of these radiolucent lesions, however, often show irregular scalloping
- 16. DESMOPLASTIC AMELOBLASTOMA occurin the anterior regions of the jaws particularly the maxilla resembles a fibro-osseous lesion because of its mixed radiolucent and radiopaque appearance mixed radiographic appearance is due to osseous metaplasia within the dense fi brous septa that characterize the lesion, not because the tumor itself is producing a mineralized product
- 17. DIFFERENTIAL DIAGNOSIS Odontogenickeratocyst- displaced thinning of cortical bone and associated with unerupted tooth Myxoma- condyle involved- spontaneous fracture Odontogenic myxoma- soap bubble appearance, multiple loculayion Radicular cyst – associated with apex of tooth
- 18. HISTOLOGICAL TYPES AmeloblastomaPlexiform Acanthomatous Granular Basalcell type Desmoplastic Follicular
- 19. VICKER AND GORLINCRITERIA FOR AMELOBLASTOMA Hyperchromatism of basal cell nuclei. Palisading of basal cell with polarization of nuclei away from basement membrane ( reverse polarity) Cytoplasmic vacuolization of basal call
- 20. FOLLICULAR PATTERN Mostcommon Islands of epithelium resemble enamel organ epithelium in a mature fibrous connective tissue stroma epithelial nests consist of a core of loosely arranged angular cells resembling the stellate reticulum of an enamel organ A single layer of tall columnar ameloblast-like cells surrounds this central core. The nuclei of these cells are located at the opposite pole to the basement membrane (reversed polarity). In other areas, the peripheral cells may be more cuboidal and resemble basal cells. Cyst formation is common
- 23. PLEXIFORM PATTERN consistsof long, anastomosing cords or larger sheets of odontogenic epithelium. The cords or sheets of epithelium are bounded by columnar or cuboidal ameloblast-like cells surrounding more loosely arranged epithelial cells. The supporting stroma tends to be loosely arranged and vascular. Cyst formation is relatively uncommon When it occurs, it is more often associated with stromal degeneration rather than cystic change within the epithelium
- 26. ACANTHOMATOUS PATTERN Whenextensive squamous metaplasia, often associated with keratin formation, occurs in the central portions of the epithelial islands of a follicular ameloblastoma, the term acanthomatous ameloblastoma may be confused with squamous cell carcinoma or squamous odontogenic
- 29. GRANULAR CELL PATTERN Transformation of groups of lesional epithelial cells to granular cells. cells have abundant cytoplasm filled with eosinophilic granules that resemble lysosomes ultrastructurally and histochemically. Lysosomal aggreration caused by • dysfunction of either a lysosomal enzyme or • lysosome associated protein involved in enzyme activation, enzyme targeting or lysosomal biogenesis • Increased apoptotic cell death by neighbouring neoplastic cells Aggressive lesion and marked recurrence
- 32. DESMOPLASTIC PATTERN smallislands and cords of odontogenic epithelium in a densely collagenizedstroma. Immunohistochemical studies have shown increased production of the cytokine known as transforming growth factor-b (TGF-β) in association with this lesion, suggesting that this may be responsible for the desmoplasia. Peripheral columnar ameloblast-like cells are inconspicuous about the epithelial islands Dense collagenous stroma that may appear hyalinized and hypocellular Epithelium squeezed and fragmented by dense stroma Grow in thin strand and cords of epithelium stretched out in kite tail like appearance
- 35. BASAL CELL PATTERN Least common type composed of nests of uniform basaloid cells, and they histopathologically are very similar to basal cell carcinoma of the skin. No stellate reticulum is present in the central portions of the nests. The peripheral cells about the nests tend to be cuboidal rather than columnar
- 37. HYBRID AMELOBLASTOMA Extremelyunusual Desmoplastic varient with areas of classical follicular/plexiform varient Some cases- tumor cells with granular transformation along with areas of follicular and plexiform ameloblastoma while some show basaloid changes
- 38. HEMANGIOMATOUS AMELOBLASTOMA Lesscommon Connective tissue stoma with many blood filled spaces or large endothelial lined capillaries Theories Hamartomatous malformation trauma Separate neoplasm or collision tumor
- 39. PITUITARY AMELOBLASTOMA Neoplasminvolving central nervous system Common- childhood and adolescence Origin- unobliterated portions of fetal craniopharyngeal duct, derived from Rathke’s pouch and epithelial remnants of this duct are common on adult
- 40. ADAMANTINOMA OF LONGBONES Superficial microscopic resemblance to ameloblastoma of jaws Sites tibia(common) ulna, femur, fibula
- 41. OTHER VARIENTS Acanthomatousameloblastoma keratoameloblastoma Papilliferous keratoameloblastoma
- 42. TREATMENT AND PROGNOSIS simple enucleation curettage to en bloc resection Recurrence rates of 50% to 90%
- 43. UNICYSTIC AMELOBLASTOMA 10%to 46% of all intraosseous ameloblastomas Origin 1. de novo as a neoplasm or 2. neoplastic transformation of nonneoplastic cyst epithelium Criteria for diagnosis Demonstration of single( often macro) cystic sac Odontogenic(ameloblastomatous) epithelium present usually in focal area
- 44. CLINICAL FEATURES youngerpatients mandible, posterior regions Asymptomatic large lesions may cause a painless swelling of the jaws.
- 45. RADIOGRAPHIC FEATURES circumscribedradiolucency that surrounds the crown of an unerupted mandibular third molar clinically resembling a dentigerous cyst. sharply defined radiolucent areas and are usually considered to be a primordial, radicular, or residual cyst, depending onthe relationship of the lesion to teeth in the area.
- 46.
- 48. LUMINAL UNICYSTIC AMELOBLASTOMA tumor is confined to the luminal surface of the cyst fibrous cyst wall with a lining that consists totally or partially of ameloblastic epithelium basal layer of columnar or cuboidal cells with hyperchromatic nuclei that show reverse polarity and basilar cytoplasmic vacuolization Overlying epithelial cells are loosely cohesive and resemble stellate reticulum
- 50. INTRALUMINAL UNICYSTIC AMELOBLASTOMA one or more nodules of ameloblastoma project from the cystic lining into the lumen of the cyst Nodules may be relatively small or largely fill the cystic lumen plexiform unicystic ameloblastomas- nodule of tumor that projects into the lumen demonstrates an edematous, plexiform pattern
- 52. MURAL UNICYSTIC AMELOBLASTOMA Islands of ameloblastomatous epithelium isolated in the connective tissue wall
- 54. TREATMENT AND PROGNOSIS Enucleation and curettage Recurrence rates of 10% to 20%
- 55. PERIPHERAL (EXTRAOSSEOUS) AMELOBLASTOMA Uncommon 1% to 10% of all ameloblastomas. arises from rests of dental lamina beneath the oral mucosa or from the basal epithelial cells of the surface epithelium. Histopathologically same features as the intraosseous form of the tumor.
- 56. CLINICAL FEATURES middle-agedpersons (average 52 years) Sites- posterior gingival and alveolar mucosa, common in mandibular than in maxillary areas. painless, nonulcerated sessile or pedunculated
- 57. HISTOPATHOLOGIC FEATURES islandsof ameloblastic epithelium that occupy the lamina propria underneath the surface epithelium Plexiform or follicular patterns are the most common Connection of the tumor with the basal layer of the surface epithelium is seen in about 50% of cases
- 58. TREATMENT AND PROGNOSIS respond well to local surgical excision local recurrence has been noted in 15% to 20% of cases
- 59. MALIGNANT AMELOBLASTOMA AND AMELOBLASTICCARCINOMA malignant ameloblastoma a tumor that shows the histopathologic features of ameloblastoma, both in the primary tumor and in the metastatic deposits ameloblastic carcinoma an ameloblastoma that has cytologic features of malignancy in the primary tumor,in a recurrence, or in any metastatic deposit
- 60. CLINICAL AND RADIOGRAPHIC FEATURES age - 4 to 75 years (mean age, 30 years) Metastases from ameloblastomas are most often found in the lungs- aspiration or implant metastases Cervical lymph nodes are the second most common site for metastasis of an ameloblastoma Ameloblastic carcinomas are often more aggressive lesions,with ill-defi ned margins and cortical destruction
- 61. HISTOPATHOLOGIC FEATURES primaryjaw tumor and the metastatic deposits show features that of ameloblastomas with a completely benign local course addition to cytologic features of malignancy • increased nuclear-to- cytoplasmic ratio, • nuclear hyperchromatism, • presence of mitoses • Necrosis in tumor islands areas of dystrophic calcification may be present.
- 62. TREATMENT AND PROGNOSIS Prognosis poor 50% of the patients with documented metastases and long-term follow-up have died of their disease Ameloblastic carcinoma have demonstrated a uniformly aggressive clinical course, with perforation of the cortical plates of the jaw and extension of the tumor into adjacent soft tissues.
- 63. REFERENCES Text bookof oral pathology- Shafer 8th edition. Text book of oral & maxillofacial pathology- Neville 3rd edition. https://www.researchgate.net/figure/209389225 _fig10_Fig-10-Types-of-growth-in-Unicystic- Ameloblastoma-1-Luminal-2-Intraluminal-3 https://www.facebook.com/hackdentistry