Fibrodysplasia ossificans progressiva (FOP) is a very rare disabling autosomal dominant connective tissue disorder that manifests as congenital toe malformations at birth and continues with progressive ossification of connective and muscle tissue in extraskeletal locations. It is also referred to as myositis ossificans progressiva.

Flare-ups of painful tissue swelling may occur in tendons, ligaments, fascia, and other soft tissue of the limbs, shoulder, neck, skull, and spine. These recurrences are believed to be triggered by trauma, injury, infection, and muscular injections. Heterotropic ossification of soft tissue leads to impairment of movement and eventually to restriction of lung function.

Careful early examination of congenital toe malformation, particularly in the presence of family history of ossification, can avoid delayed diagnosis and prevent continued injury, such as that caused by biopsy, inoculations, and surgery.

The US Food and Drug Administration (FDA) has approved palovarotene for the treatment of FOP in adult and pediatric patients (female patients aged 8 years and older and male patients aged 10 years and older), to reduce the volume of new heterotopic ossification.