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Case Management & Presentation by Dr. Kedar Muthe, MDS,
Professor, Dept. of Oral & Maxillo-facial Surgery,
College of Dental Sciences, Davangere



Unicystic Ameloblastomas generally resemble a dentigerous cyst clinically and radiologically, although a few are not associated with unerupted teeth. They typically occur more often in younger persons, mainly in second and third decades, than do classic intraosseous ameloblastomas (solid or multicystic ameloblastomas).

The diagnosis of unicystic ameloblastoma is based on two features: first, the lesion must be unilocular clinically and radiologically. Secondly, on microscopic examination it must appear as a single cystic lesion with the epithelial lining consisting of ameloblastoma. Moreover, there is a tendency to assume that all unilocular lesions that are diagnosed microscopically as ameloblastomas are unicystic ameloblastomas. This is not so. A unilocular lesion, on pathological examination may show features of classic intraosseous ameloblastoma.

The importance of unicystic ameloblastoma is that it possesses a much better prognosis after enucleation or curettage than does the classic intraosseous ameloblastoma. Its recurrence rate after this procedure is around 15%, whereas recurrence is much higher after curettage of intraosseous ameloblastoma. The reason for this better prognosis is that in many examples the ameloblastoma involves only the epithelial lining of the cyst or projects into the lumen. These lesions are referred as luminal or intra-luminal ameloblastomas, respectively. These lesions are confined by fibrous connective tissue wall of the cyst and are consequently removed completely if cyst is enucleated. However, other unicystic ameloblastomas may recur. These are the so called mural ameloblastomas that have involved the connective tissue wall of the cyst or possibly that have arisen from the rest of odontogenic epithelium within the wall of the cyst and have subsequently invaded the surrounding bone. At this stage, a unicystic ameloblastoma will act as a classic intraosseous ameloblastoma and has to be treated as such.

Only the unicystic ameloblastoma enjoys a good prognosis if it is confined by the fibrous connective tissue wall of the cyst. The pathologist should examine the tissue sections carefully in an attempt to determine if the ameloblastoma has penetrated the wall of the cyst, this information should be noted on the pathology report. However, this is only possible if the cyst is enucleated clearly so as to provide an intact specimen.


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