A BRIEF review of cranio-facial fibro-osseous lesions in given and 15 cases of fibrous dysplasia and ossifying fibroma are presented with clinical, radiological and histomorphological findings. After histological verification of the fibro-osseous nature of the process, 5 lesions were diagnosed on a radiological basis as fibrous dysplasia exhibiting diffuse (blending) margins, while the diagnosis of ossifying fibroma was given to 10 radiologically sharply-demarcated lesions. Both groups of lesions presented the same histomorphological features, although to a varying degree. Spheroidal calcifications, however, were identified in ossifying fibroma only, but not in all of these. Thus, the differential diagnosis of fibrous dysplasia versus ossifying fibroma rests on a radiological creiterion after the histopathologist has verified the fibro-isseiys nature of a lesion. The observation times varied from 1 ½ to 34 years. Two cases of fibrous dysplasia and 3 cases of ossifying fibroma recurred. In one case of fibrous dysplasia an osteosarcoma developed 33 years after irradiation. Pain was a common symptom in the present material.

A BRIEF review of cranio-facial fibro-osseous lesions is given and 15 cases of fibrous dysplasia and ossifying fibroma are presented with clinical, radiological and histomorphological findings. After histological verification of the fibro-osseous nature of the process, 5 lesions were diagnosed on a radiological basis as fibrous dysplasia exhibiting diffuse (blending) margins, while the diagnosis of ossifying fibroma was given to 10 radiologically sharply-demarcated lesions. Both groups of lesions presented the same histomorphological features, although to a varying degree. Spheroidal calcifications, however, were identified in ossifying fibroma only, but not in all of these. Thus, the differential diagnosis of fibrous dysplasia versus ossifying fibroma rests on a radiological criterion after the histopathologist has verified the fibro-osseous nature of a lesion. The observation times varied from 1 ½ to 34 years. Two cases of fibrous dysplasia and 3 cases of ossifying fibroma recurred. In one case of fibrous dysplasia an osteosarcoma developed 33 years after irradiation. Pain was a, common symptom in the present material.