General clinical and morphological picture
These neoplasms are relatively rare in clinical practice. Despite their predominantly benign nature, they require close attention due to their specific growth characteristics.
Tumor development occurs intraosseously. Growth is usually very slow, so the process may remain completely asymptomatic for a long time. However, over time, the locally destructive action leads to severe consequences:
- Significant deformity of the jaw bones.
- Pathological displacement and loosening of teeth.
- Tumor formation in the areas housing an impacted tooth.
- Occurrence of spontaneous jaw fractures due to bone tissue thinning.
In addition, the tumor is capable of breaking through the bone cortex: in the mandible, it can invade the soft tissues of the oral cavity, while in the maxilla, it can infiltrate the maxillary sinus. It is important to remember that with non-radical surgical removal, these neoplasms have a high tendency to recur.
Classification
According to the World Health Organization (WHO, 2005) classification, the division of these tumors is based on their histogenesis. It takes into account the complex embryogenesis of the dentomaxillary system and interactions between precursor cells of various dental tissues.
Three main groups of odontogenic tumors are distinguished:
- Of epithelial origin.
- Of mesenchymal origin.
- Of mixed origin (epithelial-mesenchymal).
Ameloblastoma
The most common and clinically significant among benign epithelial odontogenic tumors is ameloblastoma (obsolete term — adamantinoma).
Its source is odontogenic epithelium persisting from enamel organ remnants or the epithelial lining of pre-existing odontogenic cysts. The disease affects men and women with equal frequency, predominantly aged 20 to 50 years (though it can also occur in childhood).
Predilection site:
- In over 80% of cases, the body of the mandible is affected (especially the premolar and molar regions, as well as the angle and ramus of the mandible).
- The tumor arises much less frequently in the incisor region.
- In exceptional cases, extraosseous (peripheral) forms occur, which are usually located on the gingiva.
Macroscopically, two forms of ameloblastoma are distinguished:
- Solid: a dense gray node consisting entirely of tumor tissue.
- Polycystic: a lesion containing multiple cystic cavities filled with brown or clear fluid.
Briefly: answers to topical questions
Which specific neoplasms belong to odontogenic tumors of mesenchymal origin?
Benign odontogenic tumors of mesenchymal origin include myxoma, fibroma, and the cementum-producing tumor group.
- Odontogenic myxoma is a neoplasm of myxoid tissue characterized by locally destructive growth.
- Odontogenic fibroma — a tumor composed of mature fibrous tissue with small interspersed foci of odontogenic epithelium.
- Cemental tumors (cementoemas) — fibro-osseous-cemental lesions characterized generally by the presence of cementum-like tissue. This group includes cementoblastoma (true cementoma), cementing fibroma, and periapical cemento-osseous dysplasia.
Which histological variants of structure are characteristic of ameloblastoma?
Ameloblastoma is characterized by the identification of the most frequent and rare histological variants of structure.
- Follicular variant — the most typical, consisting of islands of epithelial cells resembling a developing enamel organ.
- Plexiform variant — represented by irregularly shaped epithelial strands intertwining in a network.
- Granular cell variant — belongs to rare forms of the tumor.
- Monocystic variant — a rare form representing an ameloblastoma within a cyst wall.
- Acanthomatous type — distinguished by the highest tendency to recur (they can recur even after 10 years).
Which tumors are included in the group of mixed (epithelial-mesenchymal) odontogenic neoplasms?
The group of benign odontogenic tumors of mixed epithelial-mesenchymal origin includes neoplasms consisting of both epithelial and mesenchymal structural elements.
- Ameloblastic fibroma — a tumor completely lacking hard dental tissues (enamel or dentin).
- Ameloblastic fibro-odontoma — a neoplasm similar to ameloblastic fibroma, but containing hard tissues.
- Odontoma — a hamartoma that, when fully developed, includes all dental tissues. Simple and complex odontomas are distinguished. Complex odontomas are further subdivided into mixed and compound.
To easily recognize polycystic ameloblastoma on a radiograph, think of "soap bubbles". Multilocular areas of bone destruction separated by thin bony septa are visible on the image, visually resembling a cluster of soap bubbles.
Class and exam questions
Are odontogenic tumors cancer?
In the vast majority of cases, they are benign. However, due to their locally destructive growth, their behavior can be aggressive; they destroy bone and recur if incompletely removed.
What serves as the source of development for ameloblastoma?
It develops from the odontogenic epithelium (remnants of the enamel organ) or from the epithelial lining of odontogenic cysts.
Where is ameloblastoma most commonly found?
The typical localization is the body of the mandible (molar and premolar region, ramus, and angle), accounting for over 80% of all cases.
What else to study on this topic
- Histological variants of ameloblastoma (follicular, plexiform, acanthomatous, desmoplastic, etc.)
- Non-odontogenic tumors of the jaw bones and their differences
- Metastatic lesions of the jaws (metastases of breast, lung, and renal cancer)
- Odontogenic inflammatory processes (periostitis, osteomyelitis)
- Cysts of the jaw bones and their relationship to the tumor process
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