Literature
Clinical Pearls & Morning Reports
Published October 18, 2017
Patients with eosinophilic granulomatosis with polyangiitis typically present during one of three characteristic stages: the allergic phase, the eosinophilic stage, or the vasculitic stage. Read the latest Case Records of the Massachusetts General Hospital.
Clinical Pearls
Q: Can IgG4-related disease mimic eosinophilic granulomatosis with polyangiitis?
A: Although IgG4-related disease is not considered to be a pulmonary eosinophilic disorder, it can mimic vasculitis (particularly eosinophilic granulomatosis with polyangiitis), and patients with IgG4-related disease may present with asthma, chronic sinusitis, and peripheral eosinophilia. Many patients with eosinophilic granulomatosis with polyangiitis have an elevated IgG4 level.
Q: How specific are the American College of Rheumatology’s classification criteria for eosinophilic granulomatosis with polyangiitis?
A: The American College of Rheumatology (ACR) has defined six classification criteria for eosinophilic granulomatosis with polyangiitis; additional criteria were developed in 2012, as part of the Revised International Chapel Hill Consensus Conference Nomenclature of Vasculitides. When four or more ACR criteria are present, a diagnosis of eosinophilic granulomatosis with polyangiitis has 85% sensitivity and 99.7% specificity.
Table 3. Classification Criteria for Eosinophilic Granulomatosis with Polyangiitis.
Morning Report Questions
Q: What are some of the differences between ANCA-positive and ANCA-negative cases of eosinophilic granulomatosis with polyangiitis?
A: Although most patients with granulomatosis with polyangiitis or microscopic polyangiitis are ANCA-positive, only approximately 40% of patients with eosinophilic granulomatosis with polyangiitis are ANCA-positive. The clinical manifestations of eosinophilic granulomatosis with polyangiitis differ between ANCA-positive and ANCA-negative patients. For example, ANCA-positive patients with eosinophilic granulomatosis with polyangiitis are more likely than ANCA-negative patients to have glomerulonephritis, pulmonary hemorrhage, and mononeuritis multiplex. The consensus among experts is that ANCA-positive patients with eosinophilic granulomatosis with polyangiitis tend to have better treatment responses than ANCA-negative patients.
Q: Is an indirect immunofluorescence assay of blood showing a perinuclear staining pattern diagnostic of ANCA-associated vasculitis?
A: In patients with clinical features of vasculitis, the presence of ANCA with specificity for myeloperoxidase or proteinase 3 has a high positive predictive value for a diagnosis of one of the ANCA-associated vasculitides, which include granulomatosis with polyangiitis, microscopic polyangiitis, renal-limited vasculitis, and eosinophilic granulomatosis with polyangiitis. Testing for ANCA incorporates the results of two distinct assays: an indirect immunofluorescence assay and an enzyme-linked immunosorbent assay (ELISA). In cases of ANCA-associated vasculitis, a perinuclear staining pattern typically indicates the presence of autoantibodies to myeloperoxidase. However, the indirect immunofluorescence assay alone is not sufficiently specific for establishing the presence of ANCA. It can be difficult to reliably distinguish the perinuclear staining pattern caused by ANCA from the staining pattern caused by antinuclear antibodies. Moreover, antibodies to a variety of proteins that are localized to azurophilic granules in neutrophils — including lactoferrin, human leukocyte elastase, and cathepsin G — can cause a perinuclear staining pattern.