Fibrodysplasia ossificans progressiva: CT appearance.

Twelve patients with fibrodysplasia ossificans progressiva were studied with computed tomography (CT). Characteristic swelling of the muscular fascial planes could be identified on CT scans prior to the development of ectopic ossification. Ossification could be seen on CT scans before it was apparent on plain radiographs. The pattern of ossification was similar to that seen at pathologic study, with multifocal sites developing adjacent to and extending around muscles. The appearance on CT scans confirms the hypothesis that the initial focus in fibrodysplasia ossificans progressiva is in the connective tissue.