Juvenile ossifying fibroma. An analysis of eight cases and a comparison with other fibro-osseous lesions.

Juvenile ossifying fibroma (JOF) is a well-defined clinical and histological entity that has recently been separated from other fibro-osseous lesions, including cemento-ossifying fibromas. Its biological behaviour is well defined, but unexplained. Its behaviour, clinical and histological appearance, however, bears resemblance to osteofibrous dysplasia of long bones, a lesion that in some cases has been reported to be part of a spectrum of diseases associated with adamantinoma, thus accounting for its variable biological behaviour. Eight cases of JOF were examined for islands of epithelium or single epithelial cells using immunocytochemistry. While these cases of JOF could clearly be separated from other fibro-osseous lesions, and were histologically similar to osteofibrous dysplasia, the absence of cytokeratin-positive cells in all cases suggests that another reason for its biological behaviour has still to be found.