Peripheral ameloblastoma: biological profile based on 160 cases from the literature

The present profile of the peripheral ameloblastoma (PA) is based on a lite rature survey of 160 published tumour cases. The PA is an exophytic growth localized to the soft tissues overlying the tooth-bearing areas of the jaws , the initial diagnosis often being fibrous epulis. In most cases there is no radiological evidence of bone involvement, but a superficial bone erosio n - known as cupping or saucerization - may be detected at operation. The P A accounts for 2 - 10% of all ameloblastomas. The overall average age is 52 .1 years, slightly higher for males (52.9 years) than for females (50.6 yea rs). Thus, the PA occurs at a significantly higher age than the intraosseou s ameloblastoma (IA; 37.4 years). The male/female ratio amounts to 1.9.1, a s opposed to 1.2:1 for the IA. The male/female ratio for the Japanese cases included in this survey is 2.5:1 as opposed to that of non-Japanese cases 1.4.1. As to the location of PA, the maxilla/mandible ratio is 1:2.6. The m andibular premolar region accounts for 32.6% of all sites. Five extra-gingi val lesions have been reported under the term PA. As these cases most likel y represent salivary gland tumours, they are not accepted under the diagnos is of PA. The odontogenic gingival epithelial hamartoma shows clinical, his tological and behavioural features almost identical to the PA, and it is di scussed whether this lesion and the PA should be considered one and the sam e entity. Pathogenetically, two major sources are discussed: remnants of th e dental lamina and the oral surface epithelium. Histologically, the PA con sists of proliferating odontogenic epithelium exhibiting the same histomorp hological cell types and patterns as seen in the IA. The stroma is that of a mature, fibrous connective tissue. The indolent biological behaviour dict ates a conservative therapeutical approach. It is discussed whether PA is a true neoplastic counterpart of the IA or rather an odontogenic hamartomato us lesion. Six cases of malignant PA have been reported. (C) 2001 Elsevier Science Ltd. All rights reserved.