The exact cause of eosinophilic granulomatosis with polyangiitis (EGPA) is not yet known. However, it is believed to be an autoimmune condition in which the immune system mistakenly attacks the body’s own tissues, leading to inflammation of small- and medium-sized blood vessels.

Researchers believe that a combination of genetic, environmental, and immune system factors may contribute to the development of EGPA. In some people, allergic conditions or other environmental triggers may play a role in disrupting normal immune function. However, no specific trigger has been identified as the cause of the disease.

Eosinophilic granulomatosis with polyangiitis (EGPA) can affect people of any age, but it is most commonly diagnosed in adults, particularly those in early to middle adulthood. It affects men and women at relatively similar rates. EGPA is strongly associated with asthma and allergic conditions, such as allergic rhinitis (hay fever) and nasal polyps. Although these conditions are common among people with EGPA, having allergies or asthma does not necessarily mean that a person will develop the disease.

Laboratory Tests for Eosinophilic Granulomatosis with Polyangiitis (EGPA)

Several laboratory tests can help physicians diagnose eosinophilic granulomatosis with polyangiitis (EGPA), assess disease activity, and identify possible organ involvement.

1. Measuring Eosinophils and Detecting Inflammation

A Complete Blood Count (CBC) measures the number of different blood cells, including eosinophils, a type of white blood cell that is often elevated in people with EGPA. A high eosinophil count can support the diagnosis, although other conditions can also cause eosinophilia.

Inflammation can be assessed using blood tests such as the Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP). These markers may be elevated in EGPA, but normal results do not completely exclude the disease.

2. Testing for Antineutrophil Cytoplasmic Antibodies (ANCA)

The ANCA test detects antibodies directed against certain proteins found in neutrophils, another type of white blood cell. ANCA is positive in approximately 30–40% of people with EGPA, although the proportion varies between studies and testing methods.

A negative ANCA result does not rule out EGPA. The test is most useful when interpreted alongside symptoms, examination findings, and other investigations.

3. Measuring Immunoglobulin E (IgE)

Immunoglobulin E (IgE) is an antibody involved in allergic reactions and immune responses. IgE levels are often elevated in people with EGPA, particularly those with asthma and allergic conditions. However, elevated IgE is not specific to EGPA and cannot confirm the diagnosis on its own.

4. Assessing Kidney Function

Blood and urine tests help determine whether EGPA has affected the kidneys.

• Serum creatinine: Measures a waste product in the blood and helps assess kidney function.
• Urinalysis: Checks for blood, protein, and other abnormalities in the urine that may indicate kidney inflammation or damage.
• Estimated glomerular filtration rate (eGFR): Estimates how effectively the kidneys filter waste from the blood.

These tests are important because kidney involvement may not cause obvious symptoms during its early stages.

Summary

No single blood or urine test can definitively diagnose EGPA. Physicians interpret these results together with the patient’s medical history, physical examination, imaging studies, and, when necessary, tissue biopsy findings. These investigations also help monitor disease activity, detect organ complications, and guide treatment decisions.

Tissue Biopsy in Cases of Skin or Lung Involvement

A tissue biopsy involves collecting a small sample of tissue for examination under a microscope. When eosinophilic granulomatosis with polyangiitis (EGPA) is suspected, a physician may recommend a biopsy of affected skin, lung tissue, or another involved organ to look for evidence of inflammation, eosinophil accumulation, and blood vessel damage.

The method used to obtain the sample depends on the affected area. A skin biopsy is usually performed using a small punch or surgical procedure, while a lung biopsy may require bronchoscopy or a surgical procedure, depending on the circumstances.

Biopsy findings can help support the diagnosis of EGPA and distinguish it from other conditions. However, the characteristic features of the disease may not always be present in the sample, so a negative biopsy does not necessarily exclude EGPA. The results are interpreted alongside the patient’s symptoms, blood tests, imaging studies, and other clinical findings.

X-Rays looking for lung involvement: A chest x-ray or a CT-scan of the chest are often used to look for lung involvement.

Pulmonary Function Tests (PFTs) looking for lung involvement: A PFT is often used to document the presence of lung involvement and follow the lungs to determine if the disease is improving.

Eosinophilic Granulomatosis with Polyangiitis should be treated as early and aggressively as possible to minimize damage to small blood vessels and important organs. It is also important for people to keep any asthma symptoms under control using standard asthma therapies.

A rheumatologist is usually one of the best medical specialists to help people with Eosinophilic Granulomatosis with Polyangiitis manage the disease. Some people will also need to see a lung specialist (respirologist), a nerve specialist (neurologist), or a kidney specialist (nephrologist) if the disease significantly impacts these tissues.

Medications for Eosinophilic Granulomatosis with Polyangiitis

Corticosteroids (Prednisone)

Prednisone is the primary therapy for Eosinophilic Granulomatosis with Polyangiitis. This medicine is very effective at controlling inflammation caused by the disease. As symptoms improve and markers of inflammation return to normal, the dose of prednisone can be gradually tapered (lowered) and in some patients it can be discontinued. Some patients will need to remain on a low dose of prednisone, which can be safe and effective.

Cyclophosphamide

A medication called cyclophosphamide may be required in patients whose organs are affected. It is often used with prednisone to get the disease under control.

Azathioprine (Imuran) & Methotrexate

Patients who have been on cyclophosphamide for 6 months are usually switched to azathioprine or methotrexate as a long-term maintenance therapy. In milder cases, azathioprine may be used to induce remissi

Causes of Eosinophilic Granulomatosis with Polyangiitis (EGPA)

The exact cause of eosinophilic granulomatosis with polyangiitis (EGPA) remains unknown. However, it is believed to be an autoimmune and inflammatory disease in which the immune system mistakenly targets the body’s own tissues, leading to inflammation of small- and medium-sized blood vessels.

For reasons that are not yet fully understood, eosinophils, a type of white blood cell involved in allergic reactions and immune responses, can increase in number and accumulate in various tissues. This can contribute to inflammation and damage to affected organs.

EGPA is strongly associated with asthma and allergic conditions, including allergic rhinitis (hay fever) and nasal polyps. Although allergic or environmental triggers may contribute to abnormal immune activity in some people, no specific trigger has been established as the cause of EGPA.

Researchers believe that a combination of immune system dysfunction, genetic susceptibility, and environmental factors may contribute to the development of the disease. However, further research is needed to understand the underlying mechanisms.

Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as Churg–Strauss syndrome, is a rare disease that causes inflammation of small- and medium-sized blood vessels. This inflammation is called vasculitis.

EGPA can affect blood vessels throughout the body, including those supplying the lungs, sinuses, skin, nerves, and other organs. As a result, the disease can cause a wide range of symptoms and may affect several organs at the same time.

EGPA belongs to a group of conditions known as vasculitis, which are characterized by inflammation of blood vessels. This inflammation can damage surrounding tissues and interfere with the normal flow of blood to affected organs.

One of the key features of EGPA is its strong association with asthma. Most people with the condition have asthma, which may worsen before other symptoms develop. Chronic sinusitis and nasal polyps are also common.

The term eosinophilic refers to another important feature of the disease: an abnormally high number of eosinophils, a type of white blood cell involved in immune responses. These cells can accumulate in tissues and contribute to inflammation and organ damage.

There is no specific diet proven to stop AS or reverse spinal changes. A Mediterranean-style pattern—vegetables and fruit, whole grains, legumes, nuts, fish, and unsaturated fats—is a reasonable approach for overall health. Foods such as tomatoes and bell peppers can be included, but they shouldn’t be considered treatments for AS.

Tomatoes and arthritis

Tomatoes can be a nutritious addition to an arthritis-friendly diet, although they do not cure arthritis or directly reverse joint damage.

• Lycopene: Tomatoes are particularly rich in lycopene, an antioxidant that helps protect cells from oxidative stress. Cooked tomatoes and tomato products can provide especially well-absorbed lycopene.

• Vitamin C: Supports collagen formation and normal connective-tissue function.

• Antioxidants: Tomatoes contain vitamin C, carotenoids, and other plant compounds that contribute to overall antioxidant intake.

• Potential anti-inflammatory effects: Laboratory and observational research suggests that compounds in tomatoes may influence inflammatory pathways, but evidence that eating tomatoes significantly reduces arthritis pain or inflammation in people is still limited.

• Heart health: Tomatoes can contribute to a heart-healthy diet, which is particularly relevant for people with rheumatoid arthritis, because RA is associated with increased cardiovascular risk.

Some people with arthritis report that tomatoes or other nightshade vegetables worsen their symptoms. There isn’t strong scientific evidence that tomatoes generally cause arthritis inflammation or should routinely be avoided. If you consistently notice symptoms after eating a particular food, discussing this pattern with a healthcare professional or dietitian can be more useful than eliminating foods unnecessarily.

For osteoarthritis, tomatoes are best viewed as part of an overall nutritious eating pattern. For rheumatoid arthritis, diet can complement medical treatment but shouldn’t replace disease-modifying medication when it is prescribed.