Increased IgG4-Positive Plasma Cells in Granulomatosis with Polyangiitis: A Diagnostic Pitfall of IgG4-Related Disease

<table>Parenchymal necrosis with palisading granuloma, necrotizing vasculitis, and mixed inflammatory infiltrates, characteristic of GPA (hematoxylin and eosin, 100x original magnification).</table>

International Journal of Rheumatology

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Figure 2

Figure 2: Increased IgG4-Positive Plasma Cells in Granulomatosis with Polyangiitis: A Diagnostic Pitfall of IgG4-Related Disease 