The word eosinophilic refers to the initially high blood levels of a type of white blood cell called eosinophils. The word fasciitis refers to inflammation of the fascia, which is the tough fibrous tissue that lies on top of and between the muscles.
The cause of eosinophilic fasciitis is unknown. The disorder occurs mainly in middle-aged men but may occur in women and children.
The usual initial symptoms of eosinophilic fasciitis are pain, swelling, and inflammation of the skin, particularly over the inside of the arms and the front of the legs. The skin of the face, chest, and abdomen may occasionally be affected. Typically, the fingers and toes are not affected.
Symptoms may first be noticed after strenuous physical activity. Symptoms usually progress gradually. After weeks, the inflamed skin begins to harden, eventually acquiring a texture similar to an orange peel.
As the skin gradually hardens, the arms and legs become difficult to move. Eventually, the arms and legs may become permanently frozen in unusual positions (contractures) if the disease is not treated early. Weight loss and fatigue are common. Muscle strength does not usually decrease, but muscle and joint pain may occur. Rarely, if the arms are involved, the person may develop carpal tunnel syndrome.
Sometimes, the numbers of red blood cells and platelets in the bloodstream become very low, resulting in fatigue and a tendency to bleed easily. Rarely, the person develops a blood disorder, such as failure to produce red blood cells (called aplastic anemia), a low number of platelets (which help blood clot) that causes bleeding, or cancer of a specific type of white blood cells (lymphoma).
A doctor suspects eosinophilic fasciitis because of its typical symptoms.
The diagnosis of eosinophilic fasciitis is confirmed by taking a biopsy of affected skin and fascia and testing the samples. The biopsy sample must include all skin layers down to the muscle.
Blood tests are also done. Blood tests show that the number of eosinophils in the blood and the erythrocyte sedimentation rate (ESR) are increased. (The ESR is a test for inflammation and measures the rate at which red blood cells settle to the bottom of a test tube containing blood.) These increases indicate inflammation. Although blood test results can help doctors diagnose eosinophilic fasciitis, they alone cannot confirm a definite diagnosis of eosinophilic fasciitis because sometimes the abnormalities they detect are present in healthy people or in people who have other disorders. The diagnosis of eosinophilic fasciitis is based on all of the information doctors gather, including symptoms, physical examination results, and all test results.
Magnetic resonance imaging (MRI) can also help make the diagnosis but is not as conclusive as biopsy.
Most people respond rapidly to high doses of the corticosteroid prednisone. Treatment of eosinophilic fasciitis should be started as early as possible to prevent scarring, tissue loss (atrophy), and contractures. Corticosteroids do not cure tissue that is already atrophied and scarred. Doses are gradually reduced, but corticosteroids may need to be continued at low levels for 2 to 5 years. Some people need corticosteroids for long periods and possibly other drugs (for example, hydroxychloroquine or the immunosuppressants methotrexate, azathioprine, rituximab, mycophenolate mofetil, or cyclosporine). People may also be given nonsteroidal anti-inflammatory drugs and histamine-2 blockers.
Contractures and carpal tunnel syndrome may need to be treated surgically.
Doctors continue to monitor people by doing blood tests so that, if a blood disorder develops, it can be diagnosed and treated as soon as possible.
People who are receiving immunosuppressants are also given drugs to prevent infections such as by the fungus Pneumocystis jirovecii (see prevention of pneumonia in immunocompromised people).