Makindo Medical Notes

Introduction

Ameloblastoma is a rare, benign but locally aggressive odontogenic tumour arising from the epithelial cells that form the enamel of the teeth. It most commonly occurs in the mandible (lower jaw) and can cause significant facial deformity if left untreated.

About

• Incidence: Represents about 1% of all tumours and cysts in the jaw.
• Age Group: Commonly affects adults between 30 and 50 years old, but can occur at any age.
• Location: Predominantly found in the mandible, especially the molar and ramus regions; less commonly in the maxilla.
• Histopathology: Originates from remnants of odontogenic epithelium, such as the dental lamina, enamel organ, or epithelial lining of odontogenic cysts.

Etiology

• The exact cause is unknown, but potential factors include:
  • Genetic mutations (e.g., mutations in the BRAF gene).
  • Chronic inflammation or irritation.
  • Association with impacted teeth or odontogenic cysts.

Clinical Presentation

• Often asymptomatic in early stages and discovered incidentally on radiographs.
• Painless swelling or expansion of the jaw.
• Facial asymmetry.
• Loosening or displacement of teeth.
• Occasionally, pain or paresthesia if the tumour compresses nerves.

Radiographic Features

• On imaging studies like panoramic radiographs or CT scans:
  • Multilocular ("soap bubble" or "honeycomb") radiolucent lesions.
  • Well-defined radiolucent area with cortical bone expansion and thinning.
  • Root resorption of adjacent teeth may be observed.

Histological Subtypes

• Conventional (Solid/Multicystic) Ameloblastoma: Most common type, tends to be aggressive with a higher recurrence rate.
• Unicystic Ameloblastoma: Appears as a single cystic lesion, often less aggressive.
• Peripheral Ameloblastoma: Occurs in the soft tissues overlying the jawbone.
• Desmoplastic Ameloblastoma: Characterized by extensive stromal collagenization.

Management

• Surgical Treatment: The mainstay of treatment is surgical excision.
  • Resection: Wide local excision with margins to reduce recurrence risk.
  • Curettage: Less invasive but associated with higher recurrence rates; may be considered for smaller lesions.
• Reconstruction: May require bone grafting or reconstructive surgery to restore jaw function and appearance.
• Follow-up: Long-term monitoring is essential due to the potential for late recurrence.

Prognosis

• Generally good with appropriate surgical management.
• Recurrence rates vary depending on the type of surgery:
  • Lower recurrence with radical resection.
  • Higher recurrence with conservative treatments like enucleation or curettage.
• Malignant transformation to ameloblastic carcinoma is rare.

References

• Philipsen HP, Reichart PA. "Classification of odontogenic tumours. A historical review." Journal of Oral Pathology & Medicine. 2006.
• Speight PM, Takata T. "New tumour entities in the 4th edition of the World Health Organization Classification of Head and Neck Tumours: odontogenic and maxillofacial bone tumours." Virchows Archiv. 2017.