Maxillary ameloblastoma: report of an unusual case

Hamartomatous proliferations of odontogenic epithelium within the jaws: a potential histogenetic source of intraosseous epithelial odontogenic tumors

BACKGROUND

The jawbone is replete with a vestige of odontogenesis. The overall consensus is that intraosseous remnants of the enamel organ and dental lamina are the only histogenetic option for central epithelial odontogenic tumors. Curiously, incipient tumors or possible precursor conditions of residual odontogenic epithelium have rarely been reported in the literature.

METHODS

We microscopically evaluated 39,660 biopsy samples to determine the presence of a tumor-like odontogenic epithelial nodule in the maxilla and mandible.

RESULTS

Seven intraosseous specimens that associated with a focal proliferation of odontogenic epithelium were retrieved. Six hamartomatous processes showed four different morphologic patterns comparable with the tumor nests comprising ameloblastoma (n = 1), squamous odontogenic tumor (n=1), calcifying epithelial odontogenic tumor (n=2) and calcifying cystic odontogenic tumor (n=2). Among six lesions, four were the intrafollicular development. The remaining case of interest was multiple hyperplastic clear rests of Malassez in association with an impacted tooth.

CONCLUSION

Although it is impossible to predict the fate of these microscopic structures of hamartomatous character, the present case series indicates that any of the dormant embryonic residues of odontogenic epithelium can return to an active state, capable of non-reactive, probably neoplastic proliferation of pathological significance.

Ameloblastoma in children

PURPOSE

The purpose of this report was 1) to report the experience of the University of Maryland, Department of Oral and Maxillofacial Surgery (OMS Department) in the treatment of ameloblastoma in children and 2) to review the world literature on the treatment of ameloblastoma in children from 1970 to 2001.

METHODS AND MATERIALS

This study first reviews the experience of the OMS Department of the University of Maryland with ameloblastomas in children and then reviews the literature on this subject. The first part of the study was undertaken by a retrospective chart review of all patients with a diagnosis of ameloblastoma in the OMS Department between May 1991 and December 1999. The literature on ameloblastoma in Western societies and Africa was separately reviewed from 1970 through 2001. Reports earlier than 1970 were not reviewed, as the histologic diagnosis of ameloblastoma was not well defined before that period.

RESULTS

In the Maryland series, 11 patients under the age of 20 years with ameloblastoma were treated. Eight patients were seen primarily, and 3 presented with recurrent lesions. The average age was 15.5 years; 5 of 11 patients were black, and 9 of 11 tumors were unicystic ameloblastomas. The literature review showed 85 children in the Western reports and 77 reported from Africa. The average ages were 14.3 and 14.7 years, respectively, but unicystic ameloblastomas accounted for 76.5% of the Western and only 19.5% of the African children, with an increased frequency of occurrence in the mandibular symphisis in African (44.2%) versus Western (5.8%) patients. Analysis of recurrence after enucleation of unicystic ameloblastomas in 20 children followed at least 5 years or until recurrence showed a recurrence of 40%.

CONCLUSIONS

Ameloblastomas in children differ from adults, with a higher percentage of unicystic tumors. African children appear to resemble the adult pattern. Although enucleation has been claimed to give acceptable recurrence rates in unicystic ameloblastoma, there are no large series with long follow-up in children. The histologic pattern that exhibits mural invasion in unicystic ameloblastoma suggests that more aggressive surgery is necessary.

An anatomical classification of maxillary ameloblastoma as an aid to surgical treatment

Maxillary ameloblastoma is a different entity from its mandibular counterpart. It is reported to behave more aggressively and have a poorer prognosis. Eleven maxillary ameloblastomas (three recurrent) are reported with a follow-up ranging from 1 month to 12 years with no recurrences. It is proposed that radical treatment of these tumours, with good reconstruction, can give satisfactory function and survival. To that end, the tumours have been classified as to their position in the maxilla and surgical resection related to this.

Ameloblastoma: biological profile of 3677 cases

Available literature on ameloblastoma of the jaw was reviewed, including publications from 1960 to 1993, and compared to the latest larger review, published by Small and Waldron in 1955. The average age of patients with ameloblastoma is 36 years. In developing countries ameloblastomas occur in younger patients. Men and women are equally affected. Women are 4 years younger than men when ameloblastomas first occur, and the tumours appear to be larger in females. Dominant clinical symptoms such as painless swelling and slow growth are non-characteristic. The ratio of ameloblastoma of the mandible to maxilla is 5 to 1. Ameloblastomas of the mandible occur 12 years earlier than those of the maxilla. Ameloblastomas occur most frequently in the molar region of the mandible. In Blacks, ameloblastomas occur more frequently in the anterior region of the jaws. Radiologically, 50% of ameloblastomas appear as multilocular radiolucent lesions with sharp delineation. Histologically, one-third are plexiform, one-third follicular; other variants such as acanthomatous ameloblastoma occur in older patients. Two percent of ameloblastomas are peripheral tumours. Unicystic ameloblastomas occurring in younger patients have been found in 6%. Detailed data on 345 patients with ameloblastoma were evaluated for clarification of therapeutic approaches. Chemotherapy and radiation seem to be contraindicated. Ameloblastomas of the maxilla should be treated as radically as possible, ameloblastomas of the mandible should also be treated radically. However, ameloblastomas which radiologically appear as unilocular lesions may be treated conservatively (enucleation, curettage), whenever all areas of the cystic lumen are controllable intraoperatively. Unicystic ameloblastomas occurring in patients 15 years younger than those with multisystic ameloblastoma may be treated conservatively except in cases with invasion of epithelium into the cyst wall. Different recurrence rates have been found for histological variants of the ameloblastoma. Follicular ameloblastomas appear to recur more often than the plexiform type. Unicystic ameloblastomas reveal lower recurrence rates than "non-unicystic" ameloblastomas. The peripheral type of ameloblastoma may be excised, since conservative therapy results in low recurrence rates. Postoperative follow-up is most important in the therapy of ameloblastoma, because more than 50% of all recurrences occur within 5 years postoperatively.