Churg Strauss syndrome (allergic granulomatosis)

What is Churg Strauss syndrome?

Churg Strauss syndrome is a rare disease that affects the lungs, the skin and sometimes other organs. It is also known as allergic granulomatosis.

The main features of Churg Strauss syndrome are:

• Asthma
• Eosinophil infiltration in the lungs
• Eosinophils in the blood
• Vasculitis (inflamed blood vessels).

Eosinophils are a type of white blood cell. They are often increased in number in allergic disorders. Tissue biopsy in Churg Strauss syndrome also shows inflamed blood vessels and granulomas (clusters of mixed chronic inflammatory cells).

What are the symptoms of Churg Strauss syndrome?

Churg Strauss syndrome has been divided into 3 distinct phases, which may or may not be sequential. Symptoms depend upon the phase and organs involved.

Prodromal phase	Respiratory symptoms dominate, especially asthma Allergic rhinitis may also occur
Second phase	Peripheral blood eosinophilia Eosinophilic tissue infiltration in the lungs and/or intestine Weight loss, fever, sweats, abdominal pain and diarrhoea may occur
Vasculitic phase	May involve any organ: the heart is most frequently involved but the lung, kidney, lymph nodes and muscle can also be affected Symptoms may include bloody diarrhoea, blood in the urine, joint aches, inflammation of the heart, convulsions, coma and damage to skin nerves Asthma may lessen as the disease progresses Skin involvement occurs in more than two thirds of patients: Blisters, bleeding areas and nodules (lumps), often with central black dimple due to tissue breakdown (necrosis). Commonly on backs of arms or fronts of legs, especially elbows and knees. Scalp or trunk may be involved. Crops of new lesions may appear over months.

At least half of deaths in Churg-Strauss syndrome are due to heart involvement.

Churg-Strauss cutaneous vasculitis
before & after debridement

What is the cause of Churg Strauss syndrome?

The cause of Churg Strauss syndrome is uncertain but the presence of asthma, eosinophilia and raised immunoglobulin E levels suggest an allergic process.

It has been associated with drug sensitivities to penicillin, penicillamine, iodides, leukotriene modifiers and mesalazine in some patients.

Investigations

There is no specific blood test for Churg Strauss syndrome. Investigations usually include:

• Complete blood count
• Rheumatoid factor (RhF), antinuclear antibody (ANA), antineutrophil antibodies (ANCA)
• Kidney, liver and muscle function tests as indicated by symptoms and signs

Imaging studies may include X-rays of the lungs and sinuses, and electrocardiogram (ECG).

Skin biopsy and/or kidney biopsy may demonstrate the diagnostic combination of tissue eosinophilia, vasculitis and granuloma formation.

Management

Systemic corticosteroids are the first-line therapy for Churg-Strauss syndrome. Mild disease may initially be treated with oral corticosteroids, but most authors suggest beginning therapy for extensive disease with intravenous (IV) corticosteroids. Treatment with steroids has improved the survival from 50% at 3 years to 75% at 8 years. They are usually prescribed long-term.

The patient's response to corticosteroids is often dramatic. Within 1-2 weeks eosinophilia, the ESR and muscle enzyme levels may normalize. Corticosteroids can then be tapered, and remission is normally sustained. Low-dose prednisone may be continued for residual asthma or other symptoms.

If vasculitic symptoms are uncontrolled or if large doses of steroids are required, cyclophosphamide may be used. This appears to improve outcome in severe disease and may reduce the chance of relapse.

Other medications reported to be useful in Churg Strauss syndrome include:

• Methotrexate
• Tumour necrosis factor (TNF) blockers, such as infliximab and etanercept
• Recombinant interferon (IFN)-alpha
• Rituximab

Antibiotic prophylaxis with sulfamethoxazole-trimethoprim may be advised because intense immunosuppression increases the risk of infection.

Draft 31 March 2008