Churg-Strauss Syndrome (CSS), also called Eosinophilic Granulomatosis with Polyangiitis (EGPA), is a rare autoimmune disease that predominantly affects the blood vessels, leading to widespread inflammation. While this vasculitis can target many organs in the body, the lungs are particularly vulnerable. Respiratory symptoms are often the first indicators of the disease and can be one of its most challenging aspects. In fact, many patients first present with symptoms that resemble asthma or other lung conditions, often leading to a delayed diagnosis.
The impact of CSS on the lungs varies greatly from person to person, ranging from mild respiratory symptoms to severe, life-threatening complications. Understanding how the disease affects the lungs is critical for managing both the symptoms and the long-term progression of CSS.
For many individuals with CSS, the first sign of the disease is asthma. In fact, asthma occurs in more than 90% of patients diagnosed with CSS, often appearing years before the full syndrome manifests. Unlike typical asthma, which may be manageable with standard treatments, asthma associated with CSS is often severe, persistent, and resistant to usual therapies.
Asthma in CSS typically arises from eosinophilic inflammation in the airways. Eosinophils, a type of white blood cell, are overproduced in CSS, and they infiltrate the lungs, causing swelling and narrowing of the airways. This leads to common asthma symptoms, such as:
What distinguishes asthma in CSS from other forms of asthma is its refractory nature. While inhalers and corticosteroids may provide temporary relief, the asthma tends to persist and worsen over time, as the underlying vasculitis and eosinophilia continue to damage the lungs.
As the disease progresses, eosinophils not only affect the airways but also begin to infiltrate the lung tissue itself, leading to eosinophilic pneumonia. This is a more severe condition than asthma, characterized by inflammation of the lung's air sacs (alveoli) due to an accumulation of eosinophils.
Eosinophilic pneumonia can cause a range of symptoms, including:
The lung inflammation in eosinophilic pneumonia often shows up on chest X-rays or CT scans as abnormal, patchy areas of increased opacity, often referred to as pulmonary infiltrates. These infiltrates represent regions of the lung where eosinophils have gathered and caused inflammation, disrupting normal lung function.
Unlike infections such as bacterial pneumonia, eosinophilic pneumonia does not respond to antibiotics. Instead, corticosteroids are the mainstay of treatment, as they help reduce inflammation and suppress the immune system's overactivity. However, without adequate treatment, eosinophilic pneumonia can lead to long-term lung damage.
In some cases, CSS may cause pleural effusion, which is the buildup of fluid between the layers of tissue that line the lungs (pleura). This fluid accumulation can compress the lungs, making it difficult to breathe and leading to pleuritic chest pain (sharp pain that worsens with deep breathing or coughing).
The presence of pleural effusion in CSS is typically due to inflammation of the pleura, driven by the same immune dysregulation that causes vasculitis in other parts of the body. The fluid may contain high levels of eosinophils, further indicating the disease's involvement.
While pleural effusion itself is not usually life-threatening, it can cause significant discomfort and breathing difficulties. Treatment involves draining the excess fluid and using corticosteroids to reduce the underlying inflammation. If left untreated, large pleural effusions can put pressure on the lungs and lead to respiratory distress.
Vasculitis, or inflammation of the blood vessels, is the hallmark of CSS. In the lungs, this vasculitis affects the small and medium-sized blood vessels, disrupting blood flow and causing damage to lung tissue. The result can be pulmonary hemorrhage (bleeding in the lungs), lung scarring, and reduced oxygen exchange.
Pulmonary hemorrhage is a rare but serious complication of CSS. It occurs when inflamed blood vessels in the lungs rupture, leading to bleeding into the air sacs. Patients with pulmonary hemorrhage may experience:
Pulmonary hemorrhage is a medical emergency that requires immediate treatment with high-dose corticosteroids or other immunosuppressive therapies to control the vasculitis and stop the bleeding.
In addition to hemorrhage, the chronic inflammation in CSS can cause scarring of the lung tissue (pulmonary fibrosis). This scarring thickens the lung tissue and makes it less elastic, reducing the lungs' ability to expand and contract with each breath. Over time, pulmonary fibrosis can lead to chronic respiratory failure, a condition in which the lungs can no longer provide enough oxygen to the body.
One of the distinguishing features of CSS is airway hyperresponsiveness - a heightened sensitivity of the airways to environmental triggers, such as allergens, smoke, or cold air. This hyperresponsiveness leads to bronchospasm, a sudden constriction of the muscles surrounding the airways, which can cause intense difficulty breathing.
Bronchospasm in CSS is often triggered by exposure to irritants, but it can also occur spontaneously due to the underlying inflammation in the airways. Patients experiencing bronchospasm may require bronchodilators, such as albuterol inhalers, to relax the airway muscles and ease breathing.
While bronchospasm is a common feature of asthma, in CSS, it is compounded by the presence of vasculitis and eosinophilia, making it more difficult to control with standard asthma treatments. As a result, patients with CSS often require more aggressive treatments, including systemic corticosteroids and immunosuppressants, to prevent recurrent bronchospasms and reduce lung inflammation.
The chronic inflammation and damage to the lungs caused by CSS can lead to long-term respiratory complications. In some cases, even after the vasculitis has been controlled, patients may be left with permanent lung damage, including bronchiectasis and pulmonary fibrosis.
Bronchiectasis: This is a condition in which the walls of the bronchi (the large airways) become permanently damaged and widened. This can lead to mucus buildup, frequent lung infections, and chronic cough. Bronchiectasis in CSS is caused by repeated inflammation and damage to the airways, particularly in cases where the disease was not diagnosed early or treated aggressively.
Pulmonary Fibrosis: As mentioned earlier, fibrosis is the scarring of lung tissue. In patients with CSS, this can develop as a result of long-term eosinophilic inflammation and vasculitis. Once fibrosis sets in, it is irreversible, and patients may experience progressive shortness of breath, especially with exertion.
In advanced cases of CSS with significant lung involvement, patients may develop chronic respiratory failure, requiring long-term oxygen therapy or, in rare cases, lung transplantation.
Managing the lung-related symptoms of CSS requires a comprehensive approach that addresses both the eosinophilic inflammation and the vasculitis. The mainstay of treatment is systemic corticosteroids, which reduce inflammation and suppress the immune system. However, long-term use of corticosteroids comes with significant side effects, so many patients may also be prescribed steroid-sparing agents, such as methotrexate, azathioprine, or cyclophosphamide.
In recent years, newer therapies, such as biologic drugs, have shown promise in treating the lung complications of CSS. These drugs, such as mepolizumab (which targets IL-5) and benralizumab (which targets the IL-5 receptor), specifically reduce eosinophil levels and help control lung inflammation without the need for high doses of corticosteroids.
For patients with severe lung involvement, pulmonary rehabilitation programs, which include breathing exercises, physical therapy, and education, may help improve lung function and quality of life.
For individuals with Churg-Strauss Syndrome, lung involvement can be one of the most challenging aspects of the disease. Early recognition of respiratory symptoms - such as asthma, eosinophilic pneumonia, and pleural effusion - is crucial for timely diagnosis and treatment. By managing lung inflammation and preventing further damage, patients can minimize the long-term impact of CSS on their respiratory health and maintain a better quality of life.