If you've been researching Churg-Strauss Syndrome (CSS), you may have come across another term: Eosinophilic Granulomatosis with Polyangiitis (EGPA). You might wonder: are they the same condition? The short answer is yes, but it's a bit more complex than that. Over the years, the name for this disease has evolved, and understanding why can give you a clearer picture of what CSS, or EGPA, actually entails.
Churg-Strauss Syndrome was first described in 1951 by Drs. Jacob Churg and Lotte Strauss. They identified a specific condition characterized by asthma, eosinophilia (high levels of eosinophils in the blood), and inflammation of blood vessels (vasculitis). For decades, this condition was known as Churg-Strauss Syndrome, named after its discoverers.
However, medical terminology has shifted in recent years to become more descriptive and specific. In 2012, the International Chapel Hill Consensus Conference on the Nomenclature of Vasculitides updated the name of Churg-Strauss Syndrome to Eosinophilic Granulomatosis with Polyangiitis (EGPA). This name better reflects the key pathological features of the disease:
The new name, EGPA, highlights these defining features of the disease and makes it easier to classify within the broader spectrum of vasculitides, which are diseases that cause inflammation of the blood vessels.
To understand how Churg-Strauss Syndrome, now EGPA, fits into the broader category of vasculitis, it's helpful to compare it to other similar conditions. Vasculitis can affect blood vessels of all sizes and can involve various organ systems, leading to a range of symptoms. CSS/EGPA falls under the category of ANCA-associated vasculitis (AAV), along with two other diseases:
All three diseases share features of small- and medium-vessel vasculitis, but they have distinct characteristics that set them apart.
While CSS/EGPA shares some similarities with GPA and MPA, such as affecting small- to medium-sized blood vessels and involving multiple organ systems, there are several differences:
Eosinophilia: One of the most significant differences between CSS/EGPA and other forms of vasculitis is the presence of eosinophilia, or high levels of eosinophils in the blood. This is a hallmark of CSS/EGPA and is not typically seen in GPA or MPA.
Asthma and Allergies: Asthma and allergic rhinitis (hay fever) are common in people with CSS/EGPA, often preceding the onset of vasculitis by years. In contrast, asthma is not usually a feature of GPA or MPA.
ANCA Positivity: ANCA, or anti-neutrophil cytoplasmic antibodies, are a type of autoantibody associated with vasculitis. While ANCA positivity is common in GPA and MPA, it is only present in about 40-50% of CSS/EGPA cases. This means that ANCA tests are less reliable as a diagnostic tool for CSS/EGPA compared to other forms of vasculitis.
Granuloma Formation: Like GPA, CSS/EGPA is characterized by the formation of granulomas - small areas of inflammation where the immune system tries to wall off perceived threats. However, these granulomas are typically found around blood vessels in CSS/EGPA, while in GPA, they are more commonly found in the respiratory tract, particularly in the nose and sinuses.
The shift from “Churg-Strauss Syndrome” to “Eosinophilic Granulomatosis with Polyangiitis” may seem confusing, but it serves several purposes:
Descriptive Accuracy: The new name provides a more detailed description of the disease's pathology. The term “Churg-Strauss Syndrome” honored the doctors who first described the condition, but it didn't convey much information about the disease itself. By contrast, the term “Eosinophilic Granulomatosis with Polyangiitis” immediately tells you that the disease involves eosinophils, granulomas, and blood vessel inflammation.
Medical Classification: As medical understanding of vasculitis has improved, there has been a push to classify diseases more precisely. CSS/EGPA is now recognized as part of the ANCA-associated vasculitides, and the new name reflects its place in this classification system.
Avoiding Eponyms: There has been a growing movement in medicine to avoid using eponyms - disease names that are derived from the names of people - because they don't provide useful information about the disease. In addition, eponyms can sometimes be problematic if the person the disease is named after was involved in unethical behavior, as has been the case with some historical figures in medicine. While this is not the case with Churg and Strauss, the trend in modern medicine is to move away from eponyms in favor of more descriptive names.
If you've been diagnosed with Churg-Strauss Syndrome or Eosinophilic Granulomatosis with Polyangiitis, the name change won't affect your treatment or the way your doctors approach your care. The terminology may vary depending on your healthcare provider, but the disease remains the same.
Your doctor may use the names CSS and EGPA interchangeably, but if you're reading more current medical literature, you'll likely see the term EGPA used more frequently. Some older sources may still refer to the condition as CSS, and the term may continue to be used in casual conversation among patients and some doctors.
It's important to note that the diagnosis of CSS/EGPA is not made based on the name but on a combination of clinical features, blood tests, imaging studies, and sometimes a biopsy. Your healthcare provider will look for the presence of eosinophilia, a history of asthma or allergic rhinitis, and signs of vasculitis in multiple organ systems.
The renaming of Churg-Strauss Syndrome to Eosinophilic Granulomatosis with Polyangiitis may also influence the way the disease is studied and understood in the medical community. As research into vasculitis continues, the more descriptive name allows researchers to better define the specific features of the disease and how it differs from other forms of vasculitis. This can lead to more targeted studies, improved treatments, and a clearer understanding of the disease's underlying mechanisms.
For patients, the name change may also affect the way the disease is perceived and understood in the general public. Many people are unfamiliar with the term "Churg-Strauss Syndrome," but the name "Eosinophilic Granulomatosis with Polyangiitis" might provide more immediate clues about the nature of the disease. The new name emphasizes the role of eosinophils and granulomas, which are key to understanding how the disease affects the body.
While the transition from Churg-Strauss Syndrome to Eosinophilic Granulomatosis with Polyangiitis may seem like a minor change, it reflects a broader trend in medicine towards more precise and descriptive disease names. For patients, the most important thing to remember is that the disease itself has not changed - only the terminology.
Whether your doctor refers to your condition as CSS or EGPA, the key features of the disease remain the same: asthma, eosinophilia, and vasculitis. Understanding the terminology can help you communicate more effectively with your healthcare team and stay informed about the latest research and treatments for this rare, yet serious, condition.