A 58-year-old female patient came to surgery department with a panoramic film that had a well-defined, unicystic radiolucency in the lower right premolar region. The incional biopsy was signed out as ameloblastoma. The surgeons performed an excisional biopsy with extensive curettage and sent the specimen to our service for histopathology. They told us that the clinical presentation was unremarkable.
On histopathology, tumor cells appeared to be organized in the form of nests were seen. The cells at the periphery of the nests were tall and columnar and had nuclei exhibiting reverse polarity. Center of the nests were more loosely arranged, resembling stellate reticulum of a developing tooth bud. These features are characteristic of ameloblastoma, more specifically follicular type in this case. Interestingly, a few tumor nests with squamous metaplasia were also noted, a feature that is prevalent in acanthomatous types of ameloblastomas.
I called this follicular ameloblastoma exhibiting areas of squamous metaplasia.
Dr. K's Comments:
Ameloblastoma:
Ameloblastoma is a benign odontogenic tumor that is seen exclusively in the jaws, because that is the only site where odontogenic epithelium exists. It is seen in individuals over the age of 40 and does not demonstrate any sex predilection. It appears as a painless mass, that can continue to grow to large proportions if not removed timely. Posterior mandibular area is the most common site of involvement.
The radiographic presentation can vary from a well-demarcated, unilocular radiolucency to large multilocular defects. Resorptions of roots in the vicinity of the tumor may also be noted.
Diagnosis can only be confirmed through incisional or excisional biopsy, depending on the size of the lesion. Although the literature describes 6 distinct histological types of ameloblastomas, suggesting that each tumor falls in either one category or the other, there is rarely a tumor that demonstrates less than two histological types. In our case the predominant type was follicular, but we also saw a small area with a plexiform appearance and some tumor islands with acanthomatous change.
The preferred form of management is marginal resection. Simple enucleation followed by curettage can leave some tumor islands behind.
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| Radiograph exhibiting a well-defined, unilocular radiolucency in the right premolar region (Courtesy: Dr. Sidra-tul-Muntaha) |
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| Multiple large nests of odontogenic epithelium with tall, columnar cells at the periphery. Squamous metaplasia can be noted in the central portion of the islands. |
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| High-power view exhibiting reverse polarity in the peripheral tumor cells |
Dr. K's Comments:
Ameloblastoma:
Ameloblastoma is a benign odontogenic tumor that is seen exclusively in the jaws, because that is the only site where odontogenic epithelium exists. It is seen in individuals over the age of 40 and does not demonstrate any sex predilection. It appears as a painless mass, that can continue to grow to large proportions if not removed timely. Posterior mandibular area is the most common site of involvement.
The radiographic presentation can vary from a well-demarcated, unilocular radiolucency to large multilocular defects. Resorptions of roots in the vicinity of the tumor may also be noted.
Diagnosis can only be confirmed through incisional or excisional biopsy, depending on the size of the lesion. Although the literature describes 6 distinct histological types of ameloblastomas, suggesting that each tumor falls in either one category or the other, there is rarely a tumor that demonstrates less than two histological types. In our case the predominant type was follicular, but we also saw a small area with a plexiform appearance and some tumor islands with acanthomatous change.
The preferred form of management is marginal resection. Simple enucleation followed by curettage can leave some tumor islands behind.
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