Adenomatoid odontogenic tumour: facts and figures

The present profile of the adenomatoid odontogenic tumour represents an upd ate based on data collected from 1991 onwards. Our present knowledge disclo ses the AOT being a benign (hamartomatous), slow growing lesion which occur s in several intraosseous (follicular (F) and extrafollicular (EF)) and one peripheral variant all having identical histology. The F and EF variants a ccount for 96 per cent of all AOT's of which 71 per cent are F variants alo ne. F and EF variants together are more commonly found in the maxilla than in the mandible with a ratio of 2.1:1. Age distribution shows that more tha n two thirds are diagnosed in the second decade of life and more than half of the cases occur within the teens (13-19 years of age). The female:male r atio for all age groups and AOT variants together is 1.9.1. The marked fema le predominance (around 3:1) among certain Asian poplulations needs further clarification. The distribution of unerupted permanent teeth found in asso ciation with the F variant shows that all four canines account for 59 per c ent and the maxillary canines alone for 40 per cent. Recent findings strong ly indicate the AOT is derived from the complex system of dental laminae or its remnants. Occurence of areas of CEOT-like tissue in an otherwise "clas sic" AOT should be considered a normal feature within the continous histomo rphological spectrum of AOT. Immunohistochemical and ultrastructural findin gs have revealed that the eosinophilic deposits or "tumour-droplets" most p robably represent some form of enamel matrix. (C) 1999 Published by Elsevie r Science Ltd. All rights reserved.