Churg–Strauss syndrome

Overview

Churg–Strauss syndrome, now more commonly known as Eosinophilic Granulomatosis with Polyangiitis (EGPA), is a rare autoimmune disease characterized by inflammation of blood vessels (vasculitis). It primarily affects small to medium-sized arteries and veins and is associated with asthma, elevated eosinophil levels in the blood, and damage to multiple organ systems, especially the lungs, skin, nerves, and gastrointestinal tract. EGPA is part of a group of disorders known as ANCA-associated vasculitides and can be life-threatening if left untreated.

Causes

The exact cause of Churg–Strauss syndrome is unknown. However, it is believed to be an autoimmune condition in which the immune system mistakenly attacks healthy tissues, leading to inflammation of blood vessels. Contributing factors may include:

• Genetic predisposition: Some individuals may have genetic variants that increase susceptibility

• Environmental triggers: Such as allergens, infections, or medications that may initiate the disease process

• Immune system dysregulation: Abnormal responses involving eosinophils and anti-neutrophil cytoplasmic antibodies (ANCAs)

In many cases, EGPA arises in people with a long history of asthma or allergic conditions such as allergic rhinitis.

Symptoms

Churg–Strauss syndrome typically progresses through three phases, though not all patients experience every phase distinctly:

1. Allergic phase: Characterized by asthma, nasal polyps, or sinusitis, often lasting years before other symptoms appear

2. Eosinophilic phase: Marked by high levels of eosinophils in the blood and tissues, leading to pneumonia-like symptoms, gastrointestinal upset, or weight loss

3. Vasculitic phase: Inflammation of blood vessels causes damage to various organs, leading to more severe symptoms

Common signs and symptoms include:

• Severe asthma or worsening of pre-existing asthma

• Fatigue, fever, and weight loss

• Skin rashes or purpura (purple spots)

• Numbness, tingling, or pain in the limbs (peripheral neuropathy)

• Abdominal pain, diarrhea, or gastrointestinal bleeding

• Shortness of breath, chest pain, or cough (lung involvement)

• Kidney dysfunction in severe cases

Diagnosis

Diagnosis of Churg–Strauss syndrome is based on clinical evaluation, laboratory testing, and imaging. Key diagnostic steps include:

• Blood tests:

  • Elevated eosinophil count

  • Increased inflammatory markers (ESR, CRP)

  • Presence of ANCAs, particularly p-ANCA (positive in ~40% of patients)

• Tissue biopsy: Confirms vasculitis and eosinophilic infiltration in affected organs (e.g., skin, nerve, lung)

• Imaging studies: Chest X-rays or CT scans to assess lung involvement

• Electromyography (EMG): May help evaluate nerve involvement

• Urinalysis: To detect kidney inflammation or proteinuria

The American College of Rheumatology (ACR) has established criteria that aid in diagnosis, requiring at least four of six specific features for classification.

Treatment

Early and aggressive treatment is essential to prevent serious organ damage. Treatment typically includes:

• Corticosteroids: Prednisone is the first-line treatment to reduce inflammation and eosinophil levels

• Immunosuppressive drugs: Such as cyclophosphamide, azathioprine, or methotrexate for patients with severe disease or organ involvement

• Biologic agents: Mepolizumab (an anti-IL-5 monoclonal antibody) is approved for treating EGPA and may reduce steroid dependence

• Supportive care: Includes management of asthma symptoms, neuropathic pain, and monitoring for side effects of therapy

Treatment is tailored to the severity of the disease and the specific organs involved. Long-term maintenance therapy is often necessary.

Prognosis

With appropriate treatment, the prognosis for Churg–Strauss syndrome has significantly improved. Most patients respond well to corticosteroids and immunosuppressive therapy, and remission is achievable in many cases. However, relapses are common and may require repeated treatment. Severe complications can occur if major organs such as the heart, kidneys, or nervous system are involved. Lifelong follow-up is usually needed to manage the disease and monitor for treatment side effects.