Ameloblastic carcinomas or malignant ameloblastoma are malignant epithelial odontogenic neoplasms with histologic features ameloblastoma.
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Epidemiology
Ameloblastic carcinomas are rare tumors approximately accounting for 1% of jaw tumors 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 anew or transform out of preexisting ameloblastomas or odontogenic cyst 2-4.
Location
The tumors are more frequently found in the posterior mandible 1,3.
Microscopic appearance
Microscopically, ameloblastic carcinomas are characterized 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 tumors 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 tumor
- 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 Richard P Elazy in 1982 4,5.
Differential diagnosis
The differential diagnosis of ameloblastic carcinomas include the following conditions 1,4:
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