Progressive ossifying fibrodysplasia is a dominant genetic disease; this means that it is caused by the mutation of a gene transmitted by at least one parent.
It is considered a rare disease, its worldwide prevalence is in fact two cases out of a million. It has no racial, geographic or gender variations.
Ossification of extra-skeletal tissues is characterized by the appearance of foci starting from childhood. In children suffering from this disease, congenital malformations of the big toes may be noted already at birth.
In the first ten years of life, the soft tissues become bony, causing a progressive loss of mobility. The first foci usually arise in areas near the spine (neck and shoulders) and spread to other joints and muscle groups (pelvis, elbows, and knees). They are often triggered by injury to the affected tissue, intramuscular injections, or viral infections.
The course of the disease is progressive and does not affect smooth tissues. The muscles of the face, the diaphragm and the heart are therefore not compromised.
Symptoms of progressive ossifying fibrodysplasia usually begin to manifest around four to six years of age. The evolution of the disease is variable, with periods of latency and aggravation. Patients suffering from this disease usually accuse:
- Painful crises and muscle inflammation that end in tissue ossification.
- Loss of mobility, partial or complete.
- Appearance of baldness and deafness in one third of cases.
Typical changes are present in some patients, along with other less specific symptoms of the disease:
- Intercurrent aplastic anemia.
- Infantile glaucoma.
- Growth delay.
Fibrodysplasia ossifying: the foci
Outbreaks occur when soft tissue ossification begins. During this phase, the patient may present with low-grade fever, general malaise, acute pain and swelling.
The duration of the outbreak varies depending on the amount of tissue that is calcified. It generally extends for a period ranging from seven to nine weeks.
Most patients feel relief once the outbreak is over. This suggests that the pain is produced by the formation of the bone and not by the new tissue that has formed.
Diagnosis of progressive ossifying fibrodysplasia is achieved by clinical evaluation. X-rays can confirm milder abnormalities of specific areas, but it is the genetic tests that confirm the diagnosis.
It is essential to make a correct differential diagnosis so as not to confuse this disease with others with similar characteristics. Examples are progressive bone heteroplasia, lymphedema, osteosarcoma, soft tissue sarcoma, and non-hereditary heterotopic ossification.
Treatment of ossifying fibrodysplasia
There is currently no definitive treatment for this disease. However, some preventive measures and adequate drug treatment will have to be followed to calm the pain.
At an outbreak, large doses of corticosteroid medications are usually prescribed for a period of 4 days. It begins 24 hours after the onset of the crisis with the aim of reducing the inflammation and edema of the tissues, characteristic of these phases.
It is advisable to prevent any muscle trauma by taking measures against falls and impacts. It will therefore be advisable to improve the safety of the home environment, to wear protections during sports, etc.
Physiotherapy can help reduce pain, but it must be gentle and always guided by a professional. Cryotherapy can also offer good results against the pain of outbreaks. Surgery and intramuscular injections are used only in cases of extreme necessity.
Life expectancy averages 50 years. Most patients lose mobility before the age of twenty. Death usually occurs from complications from chest insufficiency.
Research on this disease is currently aimed at delaying tissue ossification. Clinical trials are underway with drugs which, if taken in perfusion at the onset of the outbreak, could block soft tissue calcification.