This study will investigate how a gene mutation (change in DNA) causes the abnormal bone in fibrous dysplasia-a condition in which areas of normal bone are replaced with a fibrous growth similar to a scar. The bone abnormalities in fibrous dysplasia can occur in a single bone (monostotic fibrous dysplasia), multiple bones (polyostotic fibrous dysplasia), or in McCune Albright syndrome, in which there are associated glandular abnormalities. This study will also examine calcinosis samples that have been surgically removed from patients with juvenile dermatomyositis.