Fast Five Quiz: Fibrodysplasia Ossificans Progressiva

Dirk M. Elston, MD


January 14, 2021

Fibrodysplasia ossificans progressiva (FOP) is an extremely disabling connective tissue disorder characterized by progressive heterotopic ossification (HO). In most cases, the disease is the result of a spontaneous new mutation, but autosomal dominant cases have also been reported. The hallmark of FOP is malformation of the great toes.

FOP is ultra-rare, with a worldwide prevalence of 0.6-1.3 per million individuals. The disorder generally announces itself in early infancy with episodes of soft-tissue swelling, but in utero involvement has also been observed. FOP usually develops after trauma; flare-ups of soft-tissue swelling may be prompted by injury, intramuscular injections, viral infection, or falls. These episodes alter skeletal muscle, tendons, ligaments, fascia, and aponeuroses into heterotopic bone.

Are you familiar with this rare disease? Test your knowledge with this quick quiz.


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