Ameloblastic carcinoma

Ameloblastic carcinomas or malignant ameloblastoma are malignant epithelial odontogenic neoplasms with histologic features ameloblastoma.

Epidemiology

Ameloblastic carcinomasare rare tumours approximately accounting for 1% of jaw tumours ^1,2. They have been found in a wide age range and are more common in men ¹.

Diagnosis

The diagnosis is established histologically.

Clinical presentation

Ameloblastic carcinomas might present with symptoms such as swelling, pain, ulceration, dysphonia, or spasms of the chewing muscles ^2,3.

Complications

Ameloblastic carcinomas have the ability to metastasize ^1-3.

Pathology

Ameloblastic carcinomas form the malignant counterpart of ameloblastomas ^2,3. They might originate from anew or transform out of preexisting ameloblastomas or odontogenic cyst ^2-4.

Location

The tumoursare more frequently found in the posterior mandible ^1,3.

Microscopic appearance

Microscopically, ameloblastic carcinomas are characterised by an ameloblastoma-like appearance with the following histological features ^1-4:

• peripheral columnar cells
• variably reverse polarity
• cytological atypia with altered nuclear cytoplasm ratio
• cellular pleomorphism
• atypical mitosis
• neurovascular invasion
• necrosis

Immunophenotype

Epithelial cells might be positive for alpha-smooth muscle actin on immunohistochemistry and show a high Ki-67 index of more than 11.5% ¹.

Radiographic features

Radiographic features have been described as variable ⁴.

Plain radiograph

Ameloblastic carcinomas have been described as radiolucent but can show focal radiopaque spots ⁴. They might be unilocular or multilocular ¹, with an irregular border and signs of cortical destruction and soft tissue invasion ³.

CT

CT might show an expansile, destructive lesion with soft tissue extension ³. Large tumours might show foci of necrosis ⁴.

Radiology report

A description of the following features should be included in the radiology report:

• type location and size of the tumour
• unilocular/multilocular
• cortical destruction and soft tissue invasion
• relation to the adjacent structures and teeth

Treatment and prognosis

Treatment consists of radical excision possibly with additional radiotherapy ^1-4. The prognosis is poor. Pulmonary metastases are more common than regional lymph node metastasis and can occur early or late after surgical resection ^3,4.

History and etymology

The term ameloblastic carcinoma was first introduced by RP Elazy in 1982 ^4,5.

Differential diagnosis

The differential diagnosis of ameloblastic carcinomas include the following conditions ^1,4:

• ameloblastoma
• odontogenic keratocyst
• odontogenic myxoma
• calcifying epithelial odontogenic tumour
• primary intraosseous carcinoma