Ameloblastoma

A rare, benign tumor of the jaw

Ameloblastoma
Ameloblastoma_-_high_mag.jpg
Micrograph of an ameloblastoma showing the characteristic palisading and stellate reticulum. H&E stain.
Synonyms	Adamantinoma of the jaw
Pronunciation	/əˌmiːloʊbləˈstoʊmə/
Specialty	Oral and maxillofacial surgery, Otorhinolaryngology, Oncology
Symptoms	Painless swelling of the jaw, facial deformity, loosening of teeth
Complications	Bone destruction, recurrence, rare malignant transformation
Usual onset	Typically in adulthood (30–60 years)
Duration	Chronic, slow-growing
Types	Multicystic (solid), unicystic, peripheral, desmoplastic
Causes	Neoplastic proliferation of odontogenic epithelium; may involve mutations in the BRAF gene
Risk factors	No clear environmental risk factors; possibly genetic predisposition
Diagnosis	Radiograph (e.g., panoramic X-ray), CT scan, MRI, biopsy
Differential diagnosis	Odontogenic keratocyst, dentigerous cyst, fibrous dysplasia, osteosarcoma
Prevention	None known
Treatment	Surgical resection with wide margins; enucleation with curettage in some unicystic cases
Medication	Targeted therapies (e.g., BRAF inhibitors) under research for recurrent/metastatic cases
Prognosis	Good with complete surgical removal; high recurrence with inadequate resection
Frequency	Rare; ~1% of all jaw tumors
Deaths	Rare; malignant ameloblastoma may metastasize and be fatal

Ameloblastoma

A CT scan of a patient with an ameloblastoma.

The resected left half of a mandible containing an ameloblastoma, initiated at the third molar

Tracheal intubation is difficult in this child with a large ameloblastoma.

Ameloblastoma is a rare, benign tumor that originates in the jawbone or sometimes in the soft tissues of the mouth. It is known for its aggressive local behavior and potential to cause significant bone destruction and facial deformity. Despite being benign, ameloblastomas can recur after treatment and rarely metastasize.

Epidemiology

Ameloblastomas account for about 1% of all oral tumors and approximately 11% of all odontogenic tumors. They are most commonly diagnosed in adults between the ages of 30 and 60, with no significant gender predilection. The majority of ameloblastomas occur in the mandible, particularly in the molar and ramus regions.

Pathophysiology

Ameloblastomas arise from the remnants of the dental lamina, the epithelial lining of odontogenic cysts, or from the basal cells of the oral mucosa. The tumor is characterized by the proliferation of ameloblast-like cells, which are similar to the cells that form the enamel of teeth. These cells form nests or islands within a fibrous stroma, leading to the characteristic histological appearance.

Clinical Presentation

Patients with ameloblastoma typically present with a painless swelling in the jaw, which may be noticed incidentally or due to facial asymmetry. As the tumor grows, it can cause tooth displacement, malocclusion, and paresthesia if it impinges on the inferior alveolar nerve. In advanced cases, the tumor can cause significant bone resorption and pathological fractures.

Diagnosis

The diagnosis of ameloblastoma is primarily based on imaging studies and histopathological examination. Panoramic radiographs and CT scans are commonly used to assess the extent of the tumor and its effects on the surrounding bone. The radiographic appearance is often described as a "soap bubble" or "honeycomb" pattern due to the multilocular radiolucencies. A definitive diagnosis is made through a biopsy and microscopic examination, which reveals the characteristic ameloblast-like cells.

Treatment

The treatment of ameloblastoma typically involves surgical resection. The extent of surgery depends on the size and location of the tumor. Options include enucleation, curettage, or more extensive resection with margins to prevent recurrence. In some cases, reconstructive surgery may be necessary to restore function and aesthetics. Radiotherapy and chemotherapy are generally not effective for ameloblastomas.

Prognosis

The prognosis for patients with ameloblastoma is generally good, with a high survival rate. However, the risk of recurrence is significant, particularly if the tumor is not completely excised. Long-term follow-up is essential to monitor for recurrence. Rarely, ameloblastomas can undergo malignant transformation into ameloblastic carcinoma, which has a poorer prognosis.

Related pages

• Odontogenic tumor
• Mandible
• Oral and maxillofacial surgery