eMedicine Specialties > Dermatology > Diseases of the Vessels

Churg-Strauss Syndrome (Allergic Granulomatosis): Differential Diagnoses & Workup

Author: Claudia Hernandez, MD, Assistant Professor, Department of Dermatology, University of Illinois at Chicago College of Medicine
Contributor Information and Disclosures

Updated: Oct 26, 2009

Differential Diagnoses

Eosinophilic pneumonia
Henoch-Schönlein Purpura (Anaphylactoid Purpura)
Hypereosinophilic syndrome
Microscopic polyangiitis
Wegener granulomatosis

Other Problems to Be Considered

Allergic bronchopulmonary aspergillosis (bronchocentric granulomatosis) 
Cutaneous lymphoma 
Eosinophilic pneumonia
Hypereosinophilic syndrome 
Leukocytoclastic vasculitis
Loeffler syndrome 
Lymphomatoid granulomatosis 
Microscopic polyangiitis
Polyarteritis nodosa 
Rheumatoid arthritis
Wegener granulomatosis
Dirofilarial nodules

Workup

Laboratory Studies

• CBC count with erythrocyte sedimentation rate (ESR): Eosinophilia greater than 10% is a diagnostic criterion of the American College of Rheumatology (ACR). Treatment with steroids may mask this finding. Anemia, leukocytosis, thrombocytosis, and an elevated ESR usually accompany the vasculitic phase of Churg-Strauss syndrome (allergic granulomatosis).
• Rheumatoid factor (RF) and antinuclear antibody (ANA) testing: Some patients may have weakly positive ANA and/or RF results.
• Antineutrophilic cytoplasmic antibodies (ANCA) testing: Perinuclear ANCA directed predominantly against a myeloperoxidase was initially reported in as many as 75-80% of patients with Churg-Strauss syndrome (CSS), but in one study showed that only 13% had positive perinuclear ANCA findings. Because of the low sensitivity of this test, a negative ANCA result does not rule out Churg-Strauss syndrome (allergic granulomatosis). Classic ANCA directed against serine proteinase 3 is positive in approximately 10% of patients with Churg-Strauss syndrome (allergic granulomatosis). High titers of classic ANCA are seen more often with Wegener granulomatosis than with Churg-Strauss syndrome (allergic granulomatosis).
• Systemic vasculitis testing: Screened patients suspected to have systemic vasculitis for cryoglobulins, antiphospholipid antibodies, immunoglobulins (immunoglobulins G, A, E, and M), complement levels (CH50, C3, and C4). Immunoglobulin E levels are usually elevated in persons with Churg-Strauss syndrome (allergic granulomatosis).
• Liver function testing: Serum aspartate aminotransferase and serum alanine aminotransferase levels may indicate liver or muscle involvement. Hepatitis B and C virus serologies are recommended for suspected cases of systemic vasculitis.
• Creatine phosphokinase testing: Creatine phosphokinase levels may indicate muscle or cardiac involvement.
• Gastrointestinal testing: Stool guaiac screening can be performed to test for bleeding.
• BUN and creatinine measurements: Kidney involvement in the form of focal segmental glomerulonephritis may occur, but it is typically mild. Severe kidney involvement is more common in the other systemic vasculitides, such as Wegener granulomatosis and polyarteritis nodosa, than in Churg-Strauss syndrome (allergic granulomatosis).
• Urinalysis: Hematuria and proteinuria have been reported but are usually mild. Severe kidney involvement is more typical of the other systemic vasculitides than of Churg-Strauss syndrome (allergic granulomatosis).^1,7

Imaging Studies

• Chest radiography: Findings may be abnormal in both the eosinophilic stage and the vasculitic phase. Radiographs typically reveal transient patchy alveolar opacities, nodular infiltrates, or a diffuse interstitial pattern. Bilateral hilar adenopathy has also been reported.⁵
• Sinus radiography: Opacification of the paranasal sinuses is an ACR diagnostic criterion.
• ECG, echocardiography, and cardiac MRI: Cardiac involvement is common in Churg-Strauss syndrome (allergic granulomatosis) and may affect the pericardium, myocardium, and endocardium. Pericardial effusion, cardiomyopathy, cardiac valve abnormalities, coronary vasculitis, and granulomatous myocarditis have all been described.¹¹

Other Tests

• Any additional testing should be based on clinical history and patient symptoms.

Procedures

• Tissue biopsy: Due to ease of access, the skin, followed by the kidney, are the most frequently selected sites for biopsy. Skin biopsy specimens should be taken from a lesion less than 48 hours old. Biopsy specimens for direct immunofluorescence examination should also be obtained from a lesion less than 48 hours old.

Histologic Findings

Biopsy may reveal a variety of histologic changes, including necrotizing vasculitis of small-to-medium vessels, eosinophilic infiltration, and extravascular granulomas. Nodular lesions frequently reveal characteristic extravascular granulomas. These granulomas are not pathognomic for Churg-Strauss syndrome (allergic granulomatosis) because they are also found in persons with Wegener granulomatosis, polyarteritis nodosa, systemic lupus erythematosus, rheumatoid arthritis, lymphoproliferative disorders, and other immunoreactive disorders. Granulomas are composed of a central core of necrotic eosinophilic debris with degeneration of collagen and surrounded by a peripheral palisade of epithelioid histiocytes with few, if any, giant cells. The non-nodular lesions most often demonstrate a vasculitis or a nonspecific perivascular infiltrate of eosinophils and mononuclear cells without vasculitis.¹⁴

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