Differentiation of solitary lesions of ossifying fibroma and fibrous dysplasia can be quite difficult on histologic grounds alone, but the lesions generally can be distinguished if radiographic and clinical criteria are used together with an analysis of a biopsy specimen from the central part of the lesion. Fibrous dysplasia has a diffuse margin radiographically;
ossifying fibroma is an expansile process with a clearly defined cortical margin (being a benign tumor). Fibrous dysplasia tends to favor the maxilla whereas ossifying fibroma occurs more often in the mandible. Both are slow growing and originate early in life, but fibrous dysplasia grows endosteally and follows the general structure of the affected bone, usually producing a thickening and irregular deformation of the bone. Ossifying fibroma, by contrast, grows into and fills cavities such as the nasal cavity and accessory sinuses and destroys surrounding bone as it enlarges. Management of the two benign lesions differs considerably. Fibrous dysplasia is treated by surface sculpting whereas ossifying fibromas are managed by surgical enucleation. Juvenile aggressive forms are seen and may require en bloc resection.