Asthma is one of the most prevalent chronic respiratory conditions, affecting millions of people worldwide. However, for a small subset of individuals, the appearance of severe or late-onset asthma can be an early sign of a more serious condition: Churg-Strauss Syndrome (CSS), also known as Eosinophilic Granulomatosis with Polyangiitis (EGPA).
The connection between asthma and Churg-Strauss Syndrome is a key aspect in understanding the early manifestations of this rare disease, as asthma often precedes the systemic symptoms that define CSS. Exploring how asthma fits into the broader scope of CSS can provide essential insight into early diagnosis and help differentiate it from other respiratory diseases.
Asthma is not only a frequent companion of Churg-Strauss Syndrome—it is considered a hallmark of the disease. In fact, the vast majority of patients with CSS (around 90%) have a history of asthma, often years before any vasculitic or systemic symptoms appear. Unlike common asthma, the type associated with CSS tends to have certain unique characteristics:
Adult-Onset Asthma: While asthma commonly develops in childhood or adolescence, the asthma linked with Churg-Strauss Syndrome often begins later in life, typically in individuals aged 30 to 50 years. This late-onset asthma can be an important early warning sign for physicians, particularly if it appears alongside other allergic symptoms, such as chronic sinusitis or nasal polyps.
Severe or Worsening Asthma: The asthma seen in CSS patients is often severe and difficult to control. Even those with previously well-managed asthma may notice that their symptoms become more intense or resistant to typical treatments. Patients may require higher doses of corticosteroids to maintain control, and despite aggressive therapy, they may still experience frequent exacerbations, which can lead to a suspicion of an underlying condition like CSS.
Steroid Dependency: Because of the intensity of asthma in Churg-Strauss Syndrome, many patients become dependent on systemic corticosteroids to manage their symptoms. This long-term use of steroids, while helping to control inflammation, also contributes to complications and side effects, which can complicate the overall management of the disease.
Allergic Features: Many CSS patients report allergic rhinitis or nasal polyps along with their asthma. These allergic features often exist for years before any systemic signs of vasculitis develop, further complicating the diagnostic process. For patients with persistent asthma combined with severe allergic symptoms that do not respond well to treatment, further investigation into the possibility of Churg-Strauss Syndrome may be warranted.
For many individuals with CSS, asthma is the first noticeable symptom. However, the progression from isolated respiratory issues to a full-blown systemic vasculitic disorder may take years. In the early stages, asthma is the dominant concern, leading patients and healthcare providers to treat it as a standalone condition. Over time, the disease can evolve, affecting other organ systems in the body. This progression is marked by a transition from the initial allergic and respiratory symptoms into the eosinophilic phase and, eventually, the vasculitic phase of CSS.
Eosinophilic Phase: As the disease progresses, eosinophils—a type of white blood cell involved in allergic reactions—begin to accumulate in tissues and organs. Patients may still experience worsening asthma but may also start noticing additional symptoms, such as lung infiltrates (which can be seen on imaging), gastrointestinal issues, and skin rashes. This phase marks the beginning of systemic involvement, although asthma remains a key feature.
Vasculitic Phase: Eventually, the disease can progress to systemic vasculitis, where inflammation of small to medium-sized blood vessels occurs. At this point, asthma is often accompanied by more serious symptoms, including neurological complications, heart problems, and kidney issues. Vasculitis can affect nearly every organ in the body, leading to serious complications if left untreated.
In this way, asthma often acts as the first clue that something more serious is occurring, but it can take time for physicians to recognize the broader systemic disease at play.
Since asthma is a key symptom of Churg-Strauss Syndrome, the presence of worsening or steroid-resistant asthma in an adult should raise suspicion, especially when accompanied by other clinical signs. Here are some diagnostic considerations that can help distinguish between typical asthma and asthma caused by CSS:
Eosinophil Count: A hallmark of CSS is the presence of eosinophilia, or an elevated level of eosinophils in the blood. While many asthmatic patients may have mildly elevated eosinophil counts, those with Churg-Strauss Syndrome often show a much higher count—sometimes exceeding 10% of the total white blood cells. This eosinophilia is not only present in the blood but can also be found in lung tissues, making it a key diagnostic marker.
Additional Symptoms: Patients with CSS will typically report other symptoms beyond asthma. These can include peripheral neuropathy, which causes numbness or tingling in the extremities; skin rashes; and gastrointestinal issues like abdominal pain. The appearance of these additional symptoms often helps distinguish CSS from ordinary asthma.
Imaging Studies: Chest X-rays or CT scans of CSS patients may show lung infiltrates or nodules that are not typical in regular asthma. These abnormalities are caused by eosinophilic infiltration and can provide further clues that the patient is suffering from a systemic disease.
Biopsy: In some cases, a biopsy of affected tissues (such as the skin, lungs, or nerves) may be necessary to confirm the diagnosis of CSS. This biopsy will typically show granulomas (collections of immune cells) and vasculitis (inflammation of blood vessels), which are hallmark features of the disease.
The treatment of asthma in Churg-Strauss Syndrome is more complex than in typical cases of asthma due to the underlying systemic nature of the disease. While inhalers and other asthma medications play a role, the mainstay of treatment for CSS involves controlling the immune system to prevent further damage from eosinophilia and vasculitis.
Corticosteroids: The most common treatment for asthma in CSS is systemic corticosteroids, which help to reduce inflammation in the airways and throughout the body. While inhaled corticosteroids are often used in regular asthma, patients with CSS usually require oral steroids (such as prednisone) to keep the disease under control.
Immunosuppressive Medications: In more severe cases, especially when vasculitis is present, additional immunosuppressive drugs may be required. These drugs, such as azathioprine, methotrexate, or cyclophosphamide, work to suppress the overactive immune response seen in CSS. By controlling the immune system, these medications help reduce both asthma symptoms and the risk of systemic organ damage.
Biologics: Newer treatments for CSS include biologic medications that specifically target eosinophils, the immune cells responsible for much of the damage in CSS. One such biologic, mepolizumab, is an anti-IL-5 monoclonal antibody that reduces eosinophil levels in the blood and tissues. Clinical trials have shown that biologics like mepolizumab can help reduce the need for corticosteroids and improve asthma control in patients with CSS.
Monitoring and Follow-Up: Patients with CSS require regular follow-up with a multidisciplinary team, including a rheumatologist, pulmonologist, and possibly other specialists. Monitoring the eosinophil count, lung function, and overall disease activity is crucial for preventing flare-ups and adjusting treatment as needed.
Asthma is not just a symptom in Churg-Strauss Syndrome—it is often the first indication that something more serious may be developing. For many patients, asthma begins years before any other symptoms arise, acting as an early warning sign of systemic inflammation. By recognizing the unique characteristics of asthma in CSS—such as late onset, severity, and steroid dependency—doctors can begin to identify the disease earlier, potentially preventing the progression to more dangerous stages of CSS.
While asthma itself can be difficult to manage, the presence of Churg-Strauss Syndrome adds an additional layer of complexity. Patients with CSS require treatments that go beyond traditional asthma care, focusing on suppressing the immune system to prevent further organ damage.