Ossifying fibroma of long bone: its distinction from fibrous dysplasia and its association with adamantinoma of long bone.

Two cases of ossifying fibroma of long bones are presented. This tumor is confused with monostotic fibrous dysplasia, but can be distinguished by its intracortical location, as demonstrated radiographically, and by its histologic pattern. Distinction from fibrous dysplasia is important since ossifying fibroma of long bone is a more aggressive lesion with different therapeutic implications. It appears that ossifying fibroma and adamantinoma of long bones are somehow related, and that lesions resembling fibrous dysplasia in association with adamantinomas of long bones are actually ossifying fibromas.