[Fibrodysplasia (myositis) ossificans progressiva].

A seven-year-old boy with mental retardation and congenital skeletal malformations in the thumbs and big toes developed recurrent lumps in the shoulder and interscapular region. The lumps subsided slowly but left severe stiffness in the affected areas. The first biopsy revealed oedema and a chronic inflammatory response with fibromyxoid proliferation of the soft tissue. A second biopsy revealed ossification of muscle and fascia. The patient is a typical case of fibrodysplasia ossificans progressiva, an autosomal dominant inherited disorder characterized by congenital skeletal malformations in toes and fingers and progressive ectopic ossification, often combined with alopecia, deafness and in rare cases mental retardation. The disorder leads to severe physical disability in young age and respiratory and nutritional problems. No effective treatment is known, but it is important to avoid exacerbating factors such as biopsy, operations and intramuscular injections.