Odontogenic Tumors
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Table of Contents
AMELOBLASTIC FIBROMA
Ameloblastic Fibroma is an extremely rare true mixed benign tumor that exhibits concomitant epithelial and mesenchymal neoplastic proliferation. Ameloblastic fibro-odontoma is very similar to ameloblastic fibroma but also contains an odontoma (dental hamartoma). It may have a high recurrence rate and high rate of malignant transformation. The common clinical presentation includes:
- Well defined unilocular or multilocular radiolucency with hyperostotic margins.
- Approximately 70% in the mandible and often associated with an unerupted tooth.
- Ameloblastic fibro-odontoma has an opaque enamel/dentine component (odontoma).
- May cause jaw expansion.
- Small tumors tend to be asymptomatic.
Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:
- Odontogenic epithelium in the dental papilla-like background.
- No hard tissue formation for ameloblastic fibroma.
- Enamel matrix and dentin formation associated with odontoma (fibro-odontoma).
Your differential diagnosis should include:
- Ameloblastoma
- Dentigerous cyst
- Odontogenic keratocyst
- Odontogenic myxoma
- Giant cell granuloma
Treatment usually involves surgical excision or careful curettage.
AMELOBLASTOMA
Ameloblastoma is a rare benign but aggressive odontogenic tumor derived from the epithelium of odontogenic ectodermal origin. The cause of ameloblastoma is not well understood. Rarely they develop into a malignancy (malignant ameloblastoma or ameloblastic carcinoma). The unicystic variant of ameloblastoma is less aggressive and is managed more conservatively. The common clinical presentation includes:
- Unilocular or multilocular osteolytic radiolucency with sclerotic borders.
- Often presents in association with unerupted third molars.
- Root resorption, tooth displacement and jaw expansion possible.
- Cortical perforation may occur.
- More common in the lower jaw (80%) than in the upper jaw.
- Typically slow growing but aggressive.
Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:
- Odontogenic epithelium.
- Reverse polarization, peripheral palisading, and stellate reticulum-like cells.
- Cystic degeneration common within stellate reticulum.
- Signs of ameloblastic carcinoma include high nuclear to cytoplasmic ratio, increased mitoses, cellular atypia, perivascular invasion and necrosis.
Your differential diagnosis should include:
- Dentigerous cyst.
- Odontogenic keratocyst.
- Odontogenic myxoma.
- Giant cell granuloma.
Treatment options include:
- Local excision with or without resection for solid/multicystic lesions.
- Curettage or local excision for unilocular variants.
ODONTOGENIC MYXOMA
Odontogenic Myxoma is a rare but aggressive benign odontogenic neoplasm that probably arises from the mesenchymal portion of the tooth germ. It is the third most frequent odontogenic tumor after odontoma and ameloblastoma. The common clinical presentation includes:
- Well-defined unilocular or multilocular radiolucency that ranges from a small “honeycomb” appearance to a large “soap bubble” shape.
- Commonly associated with an unerupted tooth.
- Cortical thinning may be present but perforation is uncommon.
- Usually asymptomatic.
- May cause slow painless jaw expansion.
Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which may include:
- Minimal stellate to spindle shaped cells (hypocellular) within a myxoid background.
- Variable amounts of collagen with scattered bony trabeculae.
- Numerous engorged capillary sized vessels.
Your differential diagnosis should include:
- Other odontogenic tumors (ameloblastoma).
- Odontogenic cysts (odontogenic keratocyst, dentigerous cyst).
- Central giant cell granuloma.
Treatment options include:
- Surgical incision.
- En bloc resection.
ODONTOMAS
Odontomas are the most common hamartomatous benign mixed odontogenic tumors of the jaw, composed of all the building blocks of teeth (enamel, dentin, cementum, and pulp tissue). They develop from stimulation of the epithelial dental lamina. Variants include compound odontomas (small tooth-like structures), complex odontomas (aggregation of dentin, enamel and cementum) and cystic odontomas. The common clinical presentation includes:
- Well-defined mixed radiolucent and radiopaque lesions.
- Visible within the alveolar segment of the maxilla and mandible.
- Complex form is the most common in the mandible, compound form is the most common in the anterior maxilla.
- May contain a few small “teeth” or large numbers of tiny tooth-like structures.
- Asymptomatic and usually discovered incidentally.
- Can cause alveolar expansion, jaw expansion, and interfere with tooth eruption.
Diagnosis is based on the lesion history, clinical presentation and microscopic findings, which usually includes evidence of dental hard tissues. Your differential diagnosis should include:
- Ameloblastic fibro-odontoma.
- Adenomatoid odontogenic tumor.
- Calcifying odontogenic cyst.
- Focal sclerosing osteitis or osteoma.
Treatment usually involves conservative excision or curettage only.
