Overview
This lecture covers ameloblastoma, a common benign odontogenic tumor, including its origin, classification, clinical features, radiographic appearance, histological patterns, and treatment.
Definition and Origin
- Ameloblastoma is a true neoplasm of enamel organ tissue, with no enamel formation.
- It arises from remnants of the dental lamina or Hertwig’s epithelial root sheath.
- Named after ameloblasts, which are enamel-forming cells.
Classification of Ameloblastoma
- Clinically classified into: multicystic (solid/conventional), unicystic, and peripheral (extraosseous) types.
- Histological variants include: follicular, plexiform, acanthomatous, granular, and desmoplastic patterns.
- Malignant forms include malignant ameloblastoma and ameloblastic carcinoma.
Clinical Features
- Most common odontogenic neoplasm of the oral cavity; benign but locally aggressive.
- Predominantly affects males, Black individuals, and the mandibular molar-ramus area.
- Presents as a slow-growing, painless, hard swelling, causing facial asymmetry and potential tooth displacement.
Radiographic Features
- Appears as multilocular radiolucency with “soap bubble” or “honeycomb” appearance.
- Lesions cause buccal and lingual cortical bone expansion, root resorption, and may thin cortical plates (eggshell crackling on palpation).
- May lead to pathologic fractures; involved teeth remain vital.
Histological Patterns
- Common feature: reverse polarization (nuclei away from basement membrane).
- Follicular: islands of odontogenic epithelium with central stellate reticulum-like cells.
- Plexiform: anastomosing strands of epithelial cells in a fish-net pattern.
- Acanthomatous: squamous metaplasia in the center.
- Granular: presence of granular cells (lysosome-rich).
- Desmoplastic: dense fibrous stroma with thin cords of epithelial cells.
Special Variants and Malignant Forms
- Unicystic ameloblastoma: single cystic sac, with luminal, intraluminal, or mural histology.
- Peripheral ameloblastoma: occurs in gingiva/alveolar mucosa, more common in mandible, painless.
- Malignant ameloblastoma: histologically benign but metastasizes.
- Ameloblastic carcinoma: shows malignant cytological features in primary and metastatic sites.
Treatment
- Managed by enucleation, curettage, or en bloc resection due to high recurrence rates (50–90%).
Key Terms & Definitions
- Ameloblastoma — benign tumor of the enamel organ with no enamel formation.
- Odontogenic tumor — tumor arising from tooth-forming tissues.
- Dental lamina — embryonic structure forming teeth.
- Hertwig’s epithelial root sheath — structure guiding root formation.
- Reverse polarization — nuclei of basal cells orient away from basement membrane.
Action Items / Next Steps
- Review histological patterns and radiographic features for identification.
- Study classification and treatment options for exam readiness.