Ameloblastic Carcinoma (AC)
- Background:
- Ameloblastic carcinoma (AC) is a rare malignant odontogenic carcinoma (1.5–2% of odontogenic tumors) that has metastatic potential, more frequent in the jaw.
- It has a predilection for the male sex and the age range is wide.
- If AC shows aggressive radiologic appearances, it can be diagnosed as a malignant tumor. Otherwise, it is impossible to distinguish from ameloblastoma by radiology alone.
- Unlike ameloblastoma and metastasizing ameloblastoma, which have benign histologic characteristics, ameloblastic carcinoma demonstrates atypia, frequent mitosis, apoptosis, and necrosis.
- Clinical Presentation:
- The most common manifestation is a rapidly progressing painful swelling, which may be accompanied by ulceration, bone resorption, and dental displacement.
- Key Diagnostic Features:
- AC in x-ray can be radiolucent, unilocular, or multilocular, demonstrating a honeycomb appearance with tooth root resorption and displacement.
- CT may demonstrate the aggressive features including significant cortical and tooth root destruction.
- MRI helps to evaluate the solid component of the lesion and extension within the bone marrow. There is enhancement of solid components of the tumor, including papillary projections, walls, and septa. Dystrophic calcification and cystic changes may also be present.
- PET-CT is useful for staging and surgical planning, including lymph node evaluation.
- Differential Diagnoses:
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Ameloblastoma: Benign but aggressive intraosseous odontogenic neoplasm; uni- or multilocular radiolucent lesion with soap bubble internal pattern; well-defined margins and can have dental resorption; does not demonstrate atypia or necrosis on cytology
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Malignant ameloblastoma: Includes ameloblastic carcinoma and metastatic ameloblastoma; metastasizing ameloblastoma is rare; usually the initial lesion is multicystic or solid; the diagnosis is made retrospectively after metastases are identified, most commonly in the lung (70%); on histopathology, both the metastatic and the primary lesion must have similar histologic characteristics.
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Primary intraosseous carcinoma (PIOC): Central jaw carcinoma derived from odontogenic epithelial remnants; more frequent in the posterior body of the mandible; aggressive radiologic appearances similar to AC; differentiated by histology
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Clear cell odontogenic carcinoma: Rare odontogenic carcinoma; more frequent in the posterior body and lower ramus of the mandible; appears as a destructive radiolucency with ill-defined margins and sometimes soft tissue invasion; final diagnosis is by histology
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Benign lesions including squamous odontogenic tumor, aneurysmal bone cyst, odontogenic myxoma, and odontogenic keratocyst; benign lesions are less likely to present with destructive characteristics and soft-tissue involvement.
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Other aggressive processes that can originate or secondarily involve the jaw, including Ewing sarcoma, rhabdomyosarcoma, and Langerhans cell histiocytosis, which may be differentiated on the basis of histology
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Treatment:
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The treatment is surgical block resection with a margin of 1–2 cm.
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Radiotherapy can be given in cases with positive resection margins, positive lymph nodes, extracapsular spread, and cases with perineural invasion.
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Distant metastases suggest a poor prognosis and may appear from 4 months to 12 years postoperatively.
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