Treatment and prognosis of fibrous dysplasia: Monostotic fibrous dysplasia does not progress beyond puberty and does not require treatment. The lesions stop enlarging once the growth plates close. Surgical decompression is carried out if there is a significant mass effect. The lesions are curetted followed by bone grafting. Polyostotic form may continue to cause problems into adulthood. Involvement of shoulder and pelvic girdles in the polyostotic form can lead to severe crippling deformities and fractures that may require multiple corrective orthopedic procedures. Sarcomatous transformation to osteosarcoma, fibrosarcoma, undifferentiated pleomorphic sarcoma or chondrosarcoma is seen in less than 1% of cases (usually polyostotic forms). The image shows a focus of lipid-laded macrophages surrounded by fibroblastic stroma and irregular bony trabeculae.