Adenomatoid odontogenic tumour: facts and figures.

The present profile of the adenomatoid odontogenic tumour represents an update based on data collected from 1991 onwards. Our present knowledge discloses the AOT being a benign (hamartomatous), slow growing lesion which occurs in several intraosseous (follicular (F) and extrafollicular (EF)) and one peripheral variant all having identical histology. The F and EF variants account for 96 per cent of all AOT's of which 71 per cent are F variants alone. 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 than 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 ratio for all age groups and AOT variants together is 1.9:1. The marked female predominance (around 3:1) among certain Asian populations needs further clarification. The distribution of unerupted permanent teeth found in association with the F variant shows that all four canines account for 59 per cent and the maxillary canines alone for 40 per cent. Recent findings strongly indicate the AOT is derived from the complex system of dental laminae or its remnants. Occurrence of areas of CEOT-like tissue in an otherwise "classic" AOT should be considered a normal feature within the continuous histomorphological spectrum of AOT. Immunohistochemical and ultrastructural findings have revealed that the eosinophilic deposits or "tumour-droplets" most probably represent some form of enamel matrix.