Ameloblastoma Overview

Ameloblastoma

• Definition: Benign, locally infiltrative, slow-growing epithelial tumour arising from dental tissues.
• Key Features: Commonly affects the posterior mandible (80%), is radiolucent (dark on X-rays) due to lack of mesenchyme formation and little to no visible enamel/dentine, and typically painless unless infected.
• Epidemiology: Peak incidence in individuals aged 40-50 years. More common in Africans and Afro-Caribbeans.
• Clinical Features: Often causes expansion of the buccal (cheek) side more than the lingual (tongue) side, may displace and resorb adjacent teeth.
• Variants:
  • Solid/Multicystic: Multilocular radiolucency with radiopaque septa. Smooth, well-defined borders.
  • Unicystic: Single cystic lesion, frequently associated with unerupted lower molars. Less invasive; potentially enucleatable (removal) without recurrence.
• Radiology: Unilocular, well-defined, corticated radiolucency (dark area). Differentiate from dentigerous cyst, as they are often associated with unerupted teeth.
• Treatment: Excision with 1 cm bone margins is the gold standard. Recurrence is possible due to remaining epithelial tissue.
• Histological Variants: Includes follicular (islands of epithelium, star-shaped cells), plexiform (long strands of cells), desmoplastic (dense fibrous stroma, honeycomb-like structure), granular cell (large granular cells), and basal cell (resembles the base layer of epithelium).
• Genetic Mutations: Commonly associated with BRAF V600E mutations. Other possible mutations include RAS, SMO, and FGFR2.

Calcifying Epithelial Odontogenic Tumor (CEOT/Pindborg Tumor)

• Definition: Rare, benign epithelial tumour.
• Key Features: Presents with mixed radiolucencies and radiopacities due to internal calcification, painless and slow-growing, and commonly observed in the mandibular premolar region.
• Epidemiology: Affects adults (20-60 years, often over 50).
• Clinical Features: Painless, slow-growing, expansive. Often affects the mandibular premolar region, may cause expansion and displacement or resorption of teeth.
• Radiology: Unilocular or multilocular radiolucencies.
• Histology: Characteristic features include amyloid (pink staining, birefringent under polarized light), concentric calcifications (Liesegang rings).
• Note: Often misdiagnosed as squamous cell carcinoma due to nuclear atypia. Pathology review is crucial.

Mixed Epithelial and Mesenchymal Tumours

• Ameloblastic Fibroma: No dental hard tissue formation. Most frequent in the second decade. Posterior mandible is a common site.
• Ameloblastic Fibrodentinoma (AFD): Similar to ameloblastic fibroma, but with dentine formation.
• Ameloblastic Fibro-Odontome (AFO): Similar to ameloblastic fibroma, but with enamel and dentine formation.
  • behaves similar to Odontome.

Odontome

• Definition: Hamartoma (disorganized growth) of dental tissues.
• Types:
  • Compound Odontome: Small, tooth-like structures.
  • Complex Odontome: Mass of enamel, dentine, and pulp, without structures like teeth.

Other Odontogenic Tumours

• Adenomatoid Odontogenic Tumor (AOT): Benign tumour often mimicking a dentigerous cyst. Common in teens/early twenties, anterior maxilla, involving unerupted canines. Note mineralization visible on imaging.
• Calcifying Odontogenic Cyst (COC): Occurs in any tooth-bearing area at any age. Solid variant is more aggressive.
  • Key features Cystic and solid forms, variable mineralisation, ghost cells identifiable in the histology.
• Odontogenic Fibroma: Fibrous tumour with inactive odontogenic epithelium; commonly in the mandibular premolar area.
• Odontogenic Myxoma: Made up of myxoid (gelatinous) connective tissue; found most often in the posterior mandible. Notably, it is associated with a high recurrence rate, requiring resection.
• Cementoblastoma: Tumour of cementum (tooth root tissue). Typically painful bony swelling in the lower molar region. Presents radiographically as a radiopaque mass with a radiolucent border. Treatment often involves excision with tooth extraction.