Abstract
The purpose of this study was to review the clinical, radiological, and histopathological profile of unicystic ameloblastoma (UA) in children using data from available case reports and reviews published between 1992 and 2012. A total of 513 publications were evaluated. A structured search of the literature was performed, with predefined criteria, using computer and manual searches. An evaluation and critical appraisal was done in three separate rounds. A total of 25 articles describing 51 cases satisfied the selection criteria and were thus included in the final review. UA was mostly found to be located in the mandible, often exhibiting a unilocular radiographic image. Enucleation alone resulted in the highest recurrence rate. According to the results of this study, luminal UAs are less aggressive and respond better to conservative treatment. In contrast, plexiform and mural types frequently result in recurrence. The use of Carnoy’s solution in preventing recurrence remains to be established.
An ameloblastoma is a locally aggressive benign odontogenic tumour of the jaw. It may originate from the epithelium involved in the formation of teeth: the enamel organ, epithelial cell rests of Malassez, reduced enamel epithelium, and odontogenic cyst lining. The incidence of ameloblastomas is estimated at 0.5 per million population per year, but a higher incidence has been reported in several countries, including some in Africa and Asia.
According to the World Health Organization, ameloblastomas can be classified into four groups: (1) solid/multicystic, (2) extraosseous/peripheral, (3) desmoplastic, and (4) unicystic.
Unicystic ameloblastoma (UA) was first described by Robinson and Martinez in 1977 ; they described this entity as a special type of ameloblastoma that most often presents a radiographic appearance of a unilocular lesion, microscopically has a cystic nature, and responds better to conservative treatment. UA is observed in a rather younger age group. All of these features make it a distinguishable entity. However, Ackermann et al., on studying the histological features of UA in detail, modified the diagnostic criteria defined first by Robinson and Martinez. UA was then further classified into three groups: (1) simple or luminal type (unilocular cyst lesion with lining epithelium showing features of an ameloblastoma); (2) intraluminal type (cystic lesion comprising intraluminal tumour nodules and odontogenic epithelium with a plexiform pattern, which resembles the one seen in the plexiform solid ameloblastoma; this lesion has since also been termed a ‘plexiform unicystic ameloblastoma’ by several authors); and (3) mural or intramural type (with the presence of ameloblastomatous epithelium tumour islands in the cyst wall, which may (group 3b) or may not (group 3a) be attached to the cyst lining).
Concerning the management of UA, various treatment techniques have been used depending on the histological type and the location. The segmental or marginal resection normally used for conventional ameloblastomas has also been used in cases of UA. However, more conservative treatments have frequently been reported. Enucleation and curettage are considered the most common techniques, but many surgeons also use marsupialization to reduce the size of the lesion, followed later by enucleation. Supplementary treatments including cryotherapy, thermal or chemical cauterization, radiotherapy, and chemotherapy have also been reported in the literature.
The largest study on ameloblastoma was published by Reichart et al., who reviewed the literature from 1960 to 1993. In their meta-analysis, they identified 3677 ameloblastoma cases, of which UA comprised 6.2%. One major issue in the literature on UA is that there is not enough information concerning children, although it is well known that UA is observed quite often in the young age group.
The aim of this study was to review the profile of UA in children using available data from case reports and reviews published between 1992 and 2012. The year 1992 was selected as the cut-off, as 20 years of research was considered appropriate to allow sufficiently representative results from recent studies.
Materials and methods
Case data
The present analysis included only publications in English. All well-documented publications during the last 20 years were collected, and several clinicopathological features of each case were studied. A total of 513 publications (84 case reports and 429 reports) were evaluated in total. The following data were recorded: age (<16 years), sex, location, clinical features/symptoms, histological type, radiographic appearance, treatment, recurrence, and follow-up.
Electronic database search
A database search was done using the PubMed interface of Medline and with the following keyword combinations: (1) unicystic ameloblastoma, children, (2) unicystic ameloblastoma, and (3) ameloblastoma. The strategy was further supplemented by reference searches based on bibliographies or reference lists of all reports identified in the Medline searches.
The study inclusion and exclusion criteria are shown in Table 1 .
