Scalp Nodules as Presenting Sign of Fibrodysplasia Ossificans Progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by progressive and irreversible soft-tissue and joint ossification. FOP is caused by mutations in the ACVR1 gene; no effective treatment is known. Early clinical diagnosis is important to avoid unnecessary diagnostic and therapeutic procedures and soft-tissue injuries, all of which can exacerbate the disease.

French investigators described three infants with scalp nodules referred to a dermatology department. The scalp nodules grew rapidly and were large, firm, immobile, and painful at onset. Two infants had multiple lesions. Skull radiographs showed soft-tissue thickening, with focal ossification developing 6 to 7 months later. Nodules developed on the pati…