Ameloblastoma

Ameloblastoma . Ameloblastoma is a benign tumor of the odontogenic epithelium, characterized by its locally invasive and recurrent behavior. It usually presents as a central tumor , although there are reports that it has been recorded in soft or peripheral tissues . The term adamantinoma that was used for a long time was later replaced by that of ameloblastoma, because adamantinoma implies the presence of calcified tissue in the tumor , a characteristic that is almost never present in this neoplasm.

Summary

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  • 1 Causes
  • 2 Clinical characteristics
  • 3 Pathological anatomy
  • 4 Microscopic appearance
  • 5 Histological types or better known variants of ameloblastomas
    • 1 Ameloblastoma of the follicular type
    • 2 Plexiform ameloblastoma
    • 3 Acantomatous type ameloblastoma
    • 4 Ameloblastoma granule cell type
    • 5 Basal cell type ameloblastoma
  • 6 Sources

Causes

Most of the authors agree that ameloblastoma originates from odontogenic cells , it has not yet been possible to determine on which part of the dental apparatus this neoplasm arises.

It is believed that due to the vague similarity of some ameloblastomas to the enamel organ, the neoplasm arises from it; its origin is also attributed to epithelial remnants of the dental lamina, the lining epithelium of dentigerous cysts and the basal layer of the oral epithelium.

Clinical features

Clinical manifestations are most frequently evident in the fourth and fifth decades of life , according to studies carried out when this tumor is diagnosed, it has dimensions greater than 3 cm in diameter, because it almost always occurs asymptomatically.

It appears as an increase in volume especially in the jaw , which makes both the lingual and vestibular prominent, in rare cases it can cause a rupture of the bone wall and ulcerate the soft parts, it has no distinction by sex or race . It is considered that more than 80% of ameloblastomas affect the mandible and that of these, 70% appear in the molar region and the ascending branch. When the ameloblastoma affects the maxilla, it preferably does so in the cuspid and antral areas, with a tendency to spread to the maxillary sinus, the orbit, and the base of the skull .

41-year-old male patient with posterior bulging of the right side of the jaw, caused by an ameloblastoma.

 

Radiograph corresponding to the ameloblastoma of the 41-year-old male patient.

Radiographically the ameloblastoma offers a radiolucent image, variable in appearance; the most typical form is multilobar, where the appearance is in soap bubbles; the limits of the image may be smooth or may have certain irregularities, they may also be unilocular or associated with a retained tooth , having an appearance very similar to a dentigerous cyst or other similar entities, which explains why its radiographic image is not pathognomonic of the illness .

Pathological anatomy

From the macroscopic point of view it is characterized by being a tumor mass of varied shape; the sectional surface may be grayish white or grayish yellow and usually presents multiple and small cystic formations that alternate with solid areas, although the tumor may be totally cystic or solid. Cystic cavities usually have a smooth surface containing a fluid fluid, light brown in color and gelatinous in consistency; Sometimes the tumor mass is associated with retained teeth or is part of the wall of a dentigerous cyst . When the neoplasm reaches a certain size, the external and internal tables of the mandible are sharpened, especially towards the lingual.

Ameloblastoma, presenting its macroscopic appearance with marked expansion of bone tissue.

Microscopic appearance

Ameloblastoma is characterized by presenting a cellular pattern that sometimes resembles the enamel organ in dental development; epithelial proliferation is arranged in the form of cords or masses that can vary in extent; The central part of these structures is made up of angular cells that give it a stellate appearance, very similar to the stellate reticulum of the enamel organ; Surrounding these formations, cuboid or cylindrical cells stand out , arranged in a palisade shape, which present their nuclei more hyperchromatic than those of the central cells of the follicles. As this tumor can arise at different periods of odontogenesis, they sometimes appearbulky cells with the cytoplasm filled with eosinophilic granules.

Histological types or better known variants of ameloblastomas

  • Follicular-type ameloblastoma.
  • Plexiform ameloblastoma
  • Acanthomatous type ameloblastoma.
  • Basal Cell and Granular Cell Ameloblastoma.

Follicular-type ameloblastoma

Follicular-type ameloblastoma is characterized by the presence of masses or follicles of cells that can be polyhedral or stellate and that sometimes resemble the stellate reticulum of the enamel organ ; These follicles are surrounded by a layer of cylindrical or cubic cells , similar to the internal epithelium of the developing dental organ; The fibrous connective stroma surrounding the follicles is generally abundant and can occasionally be hyalinized around the islets of epithelium .

This type of Ameloblastoma sometimes presents small areas of squamous metaplasia in the center of some follicles, students of the subject consider that this variant should be called: follicular ameloblastoma with areas of squamous metaplasm.

Microphotograph corresponding to a histological section of a follicular ameloblastoma.

 

Microphotograph showing a histological section of another follicular ameloblastoma.

 

Microphotograph illustrating the histological appearance of a follicular ameloblastoma with squamous metaplasia.

Plexiform ameloblastoma

The plexiform ameloblastoma is mainly made up of irregular cords or masses that intersect each other in such a way that they resemble a network . The central part of these cords is made up of angular cells very similar to the stellar reticulum, which can be cylindrical or cubic. This type of ameloblastoma often has marked stromal degeneration, giving the tumor a cystic appearance.

Microphotograph corresponding to a plexiform ameloblastoma.

 

Microphotograph corresponding to a plexiform ameloblastoma.

Acanthomatous type ameloblastoma

Acanthomatous type ameloblastoma is known by this name because ameloblastomas that have extensive areas of squamous metaplasm, where most of the tumor is usually involved .

Microphotograph illustrating the histological appearance of an acanthomatous ameloblastoma.

Granular cell type ameloblastoma

The granular cell type ameloblastoma is characterized by presenting more or less extensive areas of granular cells . These cells can be cubic, cylindrical or rounded and have accumulations of acidophilic granules inside the cytoplasm.

Microphotograph in which it can be observed that the granular cells appear with a bulky cytoplasm.

 

Microphotograph corresponding to a granular cell ameloblastoma.

Basal cell type ameloblastoma

Basal cell type Ameloblastoma, corresponds to ameloblastoma that presents a histological pattern similar to basal or basal cell carcinoma of the skin , for this reason, some consider it to be its histological equivalent. It is necessary to point out that its morphology varies in relation to the histological pattern of ameloblastoma, it always tends to present characteristics of odontogenic tumor , this classification is based on the prevailing histopathological picture, since sometimes the same tumor usually has different histopathological aspects.

 

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