What are the diagnostics for Churg-Strauss syndrome (Eosinophilic Granulomatosis with Polyangiitis, EGPA)?

From the Guidelines

The diagnosis of Churg-Strauss syndrome (Eosinophilic Granulomatosis with Polyangiitis, EGPA) should be based on highly suggestive clinical features, objective evidence of vasculitis, and ANCA testing.

Key Diagnostic Features

• Highly suggestive clinical features: asthma, chronic rhinosinusitis with polyps, eosinophilia, neuropathy, lung infiltrates, eosinophilic cardiomyopathy or gastroenteritis, glomerulonephritis 1
• Objective evidence of vasculitis: histopathological findings, such as tissue eosinophilia, necrotizing vasculitis, and eosinophil-rich granulomatous inflammation 1
• ANCA testing: detectable in 30-40% of patients with EGPA, most of whom test positive for MPO-ANCA 1

Diagnostic Evaluation

• Multidisciplinary evaluation: to confirm the diagnosis and investigate the involvement of target organs, including heart, respiratory, skin, renal, and nervous system involvement, along with ANCA and eosinophilia 1
• Biopsy: recommended when feasible, but not essential to make the diagnosis of EGPA, to examine tissues and exclude differential diagnoses 1
• Investigations to be performed in selected cases: clinically driven tests, such as imaging studies and laboratory tests, to investigate specific disease manifestations and/or the positivity of baseline screening tests 1

Classification Criteria

• 1990 ACR criteria: six items, including asthma, eosinophilia, neuropathy, non-fixed lung infiltrates, paranasal sinus abnormalities, and histological evidence of extravascular eosinophils, with a sensitivity of 85% and a specificity of 99.7% 1
• 2022 ACR-EULAR criteria: weighted criteria, including a maximum eosinophil count, obstructive airway disease, nasal polyps, extravascular eosinophilic-predominant inflammation, and mononeuritis multiplex and/or motor neuropathy, with a sensitivity of 85% and a specificity of 99% 1

From the Research

Diagnostics for Churg-Strauss Syndrome (Eosinophilic Granulomatosis with Polyangiitis, EGPA)

The diagnostics for EGPA involve a combination of clinical, laboratory, and imaging tests. Some key points to consider include:

• The presence of asthma and eosinophilia are key features of EGPA, but may not be sufficient for diagnosis on their own 2, 3, 4
• The detection of antineutrophil cytoplasmic antibodies (ANCAs) can help distinguish EGPA from other hypereosinophilic syndromes, but is not present in all cases 3, 4
• Imaging tests, such as radiology, can help identify the extent of organ involvement and guide diagnosis 5
• The Five-Factor Score (FFS) can be used to assess poor-prognosis factors, such as involvement of the gastrointestinal tract, heart, and/or kidney 4
• Biomarker determination, such as characterization of mucosal airway inflammation, can be meaningful in targeted therapy and diagnosis 6
• Distinguishing EGPA from other conditions, such as chronic rhinosinusitis with nasal polyps (CRSwNP), can be clinically challenging and requires careful consideration of immunological background, diagnosis, and therapy 6

Key Diagnostic Features

Some key diagnostic features of EGPA include:

• Disseminated necrotizing vasculitis with extravascular granulomas associated with hypereosinophilia 6, 5
• Asthma and peripheral eosinophilia 2, 3, 4
• Presence of ANCAs in some cases 3, 4
• Involvement of small- and medium-size vessels 4
• Skin, lung, and peripheral nerve involvement 4

Challenges in Diagnosis

The diagnosis of EGPA can be challenging due to:

• The rarity of the condition and lack of awareness among clinicians 2
• The similarity in clinical presentation to other hypereosinophilic syndromes and systemic vasculitides 3, 6
• The absence of a biomarker that can reliably distinguish EGPA from other conditions 2, 3