When Eosinophilic Granulomatosis With Polyangiitis (EGPA) Looks Like Granulomatosis With Polyangiitis (GPA): Navigating a Complex Case of Anti-neutrophil Cytoplasmic Antibodies (ANCA) Vasculitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) is an anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis, with myeloperoxidase antibodies in 40% of cases. Proteinase 3 (PR3) positivity is rare and may overlap with granulomatosis with polyangiitis (GPA). We present a 43-year-old male with recurrent sinusitis, epistaxis, neuropathic pain, and acute kidney injury, with histopathology of kidney biopsy showing EGPA despite the absence of asthma, which is rare. His PR3 positivity and clinical presentation mimicked GPA, highlighting the diagnostic challenges of vasculitides. We report this case to highlight that EGPA can have an atypical presentation. PR3-ANCA positivity and absence of asthma do not exclude EGPA. Also, renal biopsy is crucial for diagnosis when serology and clinical features do not align.