Ameloblastic carcinoma

Last revised by Dr Joachim Feger on 14 Sep 2021

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

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.

The diagnosis is established histologically.

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

Ameloblastic carcinomas have the ability to metastasize 1-3.

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.

The tumors are more frequently found in the posterior mandible 1,3.

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

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 have been described as variable 4.

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

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 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.

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

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

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