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PubMed This is a summary of 7 peer-reviewed journal articles Updated
Rheumatology

Getting Diagnosed: The Tools and Criteria for EGPA

At a Glance

Diagnosing Eosinophilic Granulomatosis with Polyangiitis (EGPA) requires proving you have a severe eosinophilic condition, like asthma, combined with confirmed blood vessel inflammation. Doctors use blood tests, such as AEC and ANCA, alongside tissue biopsies to evaluate your clinical picture.

Navigating the diagnosis of a rare disease like EGPA can feel overwhelming. A true diagnosis requires a doctor to evaluate your entire clinical picture, including your asthma history, blood tests, and biopsies [1][2].

Essential Lab Tests and Biopsies

A diagnosis of EGPA relies on proving two things: that you have a severe eosinophilic/allergic condition, and that you have inflammation of your blood vessels (vasculitis) [3].

  1. Absolute Eosinophil Count (AEC): This measures the number of eosinophils in your blood. In EGPA, this number is typically very high, often reaching above 1.0 × 10⁹/L [1][3].
  2. ANCA Testing: This blood test looks for anti-neutrophil cytoplasmic antibodies. While roughly 60-70% of EGPA patients are ANCA-negative, testing positive for MPO-ANCA (a specific type) provides strong evidence of vasculitis [4][5].
  3. Tissue Biopsy: If your doctor takes a small tissue sample from your skin, lungs, or nerves, the results will be summarized in a pathology report. You should always feel empowered to request a copy of this report [6]. The classic signs of EGPA on a biopsy include extravascular eosinophils (eosinophils invading tissues), necrotizing vasculitis (damaged blood vessels), and granulomas (clusters of immune cells) [1][7].

The 2022 ACR/EULAR Classification Criteria

You may see references in medical literature to the 2022 ACR/EULAR Classification Criteria, which uses a point system [3][1]. It is critical to understand that this is not a diagnostic test [1].

These criteria are used strictly for research to classify patients who have already been diagnosed with vasculitis by a physician [1]. For example, a patient with standard severe asthma (+3 points) and high eosinophils (+5 points) would reach the 8 points required by the scale, but they do not have EGPA unless a doctor has separately confirmed they have blood vessel inflammation [3][2].

Once vasculitis is confirmed, doctors use this score (looking at eosinophil counts, nasal polyps, nerve damage, and ANCA status) to distinguish EGPA from other similar diseases, like GPA [1][3].

Common questions in this guide

How is EGPA diagnosed?
A formal EGPA diagnosis requires a doctor to evaluate your entire clinical picture. This involves proving you have a severe eosinophilic or allergic condition, alongside confirmed inflammation of your blood vessels.
What does a high Absolute Eosinophil Count (AEC) mean for EGPA?
In EGPA, the number of eosinophils in your blood is typically very high, often reaching above 1.0 × 10⁹/L. This elevated count is one of the key indicators doctors look for when evaluating you for this condition.
If my ANCA test is negative, can I still have EGPA?
Yes, you can still have EGPA if your ANCA test is negative. In fact, roughly 60 to 70 percent of EGPA patients are ANCA-negative, so this specific result does not rule out the disease.
What are doctors looking for in an EGPA tissue biopsy?
Pathologists examine the biopsy for classic signs of EGPA, which include eosinophils invading tissues, damaged blood vessels, and clusters of immune cells called granulomas.
Can the 2022 ACR/EULAR criteria be used to diagnose EGPA?
No, the ACR/EULAR criteria are not a diagnostic test. They are a point system used in research to classify patients who have already been formally diagnosed with vasculitis by a physician.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Can we review my pathology report together to see if there is evidence of 'extravascular eosinophilic inflammation' or 'necrotizing vasculitis'?
  2. 2.My ANCA test was negative—how does that affect our confidence in the EGPA diagnosis?
  3. 3.Are there other tests we should perform to confirm the diagnosis or rule out similar conditions?
  4. 4.How long should I expect to wait for biopsy results if one is needed?

Questions For You

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References

References (7)
  1. 1

    2022 American College of Rheumatology/European Alliance of Associations for Rheumatology Classification Criteria for Eosinophilic Granulomatosis with Polyangiitis.

    Grayson PC, Ponte C, Suppiah R, et al.

    Annals of the rheumatic diseases 2022; (81(3)):309-314 doi:10.1136/annrheumdis-2021-221794.

    PMID: 35110334
  2. 2

    The diagnosis of eosinophilic granulomatosis with polyangiitis has been 'masked' by asthma: a case report.

    Xie H, Zhang X, Zhang J, et al.

    AME case reports 2025; (9()):31 doi:10.21037/acr-24-79.

    PMID: 39866258
  3. 3

    2022 American College of Rheumatology/European Alliance of Associations for Rheumatology Classification Criteria for Eosinophilic Granulomatosis With Polyangiitis.

    Grayson PC, Ponte C, Suppiah R, et al.

    Arthritis & rheumatology (Hoboken, N.J.) 2022; (74(3)):386-392 doi:10.1002/art.41982.

    PMID: 35106968
  4. 4

    Eosinophilic granulomatosis with polyangiitis: case report and literature review.

    Alam V, Nanzer AM

    Breathe (Sheffield, England) 2022; (18(4)):220170 doi:10.1183/20734735.0170-2022.

    PMID: 36865937
  5. 5

    Differential clinicopathologic features of EGPA-associated neuropathy with and without ANCA.

    Nishi R, Koike H, Ohyama K, et al.

    Neurology 2020; (94(16)):e1726-e1737 doi:10.1212/WNL.0000000000009309.

    PMID: 32217776
  6. 6

    Churg-Strauss Syndrome or Eosinophilic Granulomatosis with Polyangiitis: Exuberant Classic Clinical Picture of a Rare Disease.

    Mukamal LV, Sodré CT, Prata LB, et al.

    Case reports in dermatology 2018; (10(2)):175-181 doi:10.1159/000489162.

    PMID: 30057533
  7. 7

    Pathological findings of hypertrophic pachymeningitis associated with eosinophilic granulomatosis with polyangiitis.

    Shiraishi W, Tsujimoto Y, Shiraishi T

    BMJ case reports 2021; (14(9)) doi:10.1136/bcr-2021-243395.

    PMID: 34544704

This page explains diagnostic tests and criteria for EGPA for educational purposes only. Always consult your healthcare provider or specialist for a formal medical diagnosis and to interpret your test results.

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