Eosinophils are a particular type of white blood cells, usually representing a small percentage (less than 8% of the total white blood cell population) that are easily stained by eosin and other dyes; they have a characteristic double-lobed nucleus. The number of these cells (eosinophil count) increases in certain illnesses, including allergies, asthma, Addison's disease, sarcoidosis, parasite infections, drug reactions, and connective tissue diseases (such as rheumatoid arthritis and scleroderma). Eosinophilic fasciitis is sometimes referred to as Shulman's syndrome.

The fascia is a sheet or band of fibrous connective tissue under the skin that covers a surface of underlying tissues. Fascia surrounds each of the muscles that move the skeleton. When the fascia is inflamed, the condition is referred to as "fasciitis."

Eosinophilic fasciitis is a rare disease that leads to inflammation and thickening of the skin and fascia underneath. In patients with eosinophilic fasciitis, the involved fascia is inflamed with the eosinophil type of white blood cells. This leads to symptoms of progressive thickening and often redness, warmth, and hardness of the skin surface.

Occasionally, the onset of eosinophilic fasciitis follows a period of exertional physical activity. Eosinophilic fasciitis is sometimes confused with eosinophilia-myalgia syndrome and scleroderma. Eosinophilic fasciitis sometimes occurs associated with cancers such as leukemia and lymphoma.

Although the cause seems related to an inflammatory response, the agent(s) that trigger the response are not yet identified. In the 1980s, there was a toxic product in some lots of L-tryptophan, an over-the-counter sleep aide that was available at the time, which caused illness similar to eosinophilic fasciitis.

Eosinophilic fasciitis causes inflammation of the tissues beneath the skin as well as sometimes in the skin. This leads to symptoms of swelling, stiffness, warmth, and pain of the involved area. Occasionally, there is discoloration of the skin over the tissues affected and the skin can appear thicker than normal. Joint contractures occur in 50%-75% of patients.

The muscle of the involved area can become weakened. Muscle enzyme blood levels can be found to be elevated in the blood, particularly the enzymes aldolase and creatine phosphokinase (CPK).

The diagnosis of eosinophilic fasciitis is made with a skin biopsy of a full thickness of involved deep skin tissue. The biopsy site is usually small, and the doctor numbs the area before the tissue is removed for study by a pathologist, dermatologist, or trained technician. In addition, the thickened fascia can be detected by MRI.

Treatment of eosinophilic fasciitis is directed at eliminating the tissue inflammation and includes aspirin, other anti-inflammatory drugs (NSAIDs), and cortisone. Many patients will improve spontaneously. Others can be afflicted with persistent tissue and joint pain, in addition to thickening of the involved tissues.

For aggressive eosinophilic fasciitis, cortisone medications (such as prednisone and prednisolone) are sometimes initially administered intravenously. Also considered are immune-suppression medications (such as methotrexate [Rheumatrex, Trexall], cyclophosphamide [Cytoxan], and penicillamine [Depen, Cuprimine]). More recently, mycophenolate mofetil (Cellcept) and rituximab (Rituxan) are being studied as potential therapies.

Medical research has shown that immune-suppression drugs, such as methotrexate, can reduce both the immune inflammation and the need for continued cortisone medications.

Eosinophilic fasciitis is treated by pediatricians, internists, dermatologists, and rheumatologists; occasionally, surgeons are consulted for deep biopsies and joint contractures.

The outlook for eosinophilic fasciitis is generally good, particularly if treated aggressively and early. Along with medications, physical therapy can be required for optimal rehabilitation. Poor function, however, is not uncommon, especially in children. Those with arthritis, atrophy of muscle, scarring limiting joint range of motion (contracture), and shortening of limb length tend to do worse.

Because we do not yet know the cause of eosinophilic fasciitis, it cannot be prevented.