Calcified spherules in fibro-osseous lesions of bone.

We present 20 examples of fibro-osseous lesions of bone, characterized by the presence of varying numbers of rounded calcified structures (calcified spherules). In the past, such lesions have been regarded as ossifying fibromas or cementifying fibromas, the latter because of their histologic similarity to jaw lesions known by that name. In the present series, six lesions showed, in addition to the calcified spherules, typical histologic features of fibrous dysplasia, while a further seven showed atypical bony structures that also suggest a link with fibrous dysplasia. This study has led us to conclude that these lesions of the extragnathic skeleton, containing rounded calcified spherules, represent a variant of fibrous dysplasia.