Renal Involvement in Eosinophilic Granulomatosis With Polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA), previously called Churg-Strauss syndrome, is a small to medium-sized systemic necrotizing vasculitis characterized by eosinophil-rich tissue infiltrates and granulomatous lesions. EGPA belongs to the larger subgroup of ANCA-associated vasculitides (AAV). However, EGPA is characterized by a distinct biological and clinical presentation when compared with granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). EGPA is typically characterized by late onset asthma, nasal and sinus-related symptoms, peripheral neuropathy and prominent peripheral blood eosinophilia.1 The prevalence of ANCA positivity in EGPA is about 40%, with predominant perinuclear staining, and exhibits an anti-MPO specificity in approximatively 65% of cases.1,2 Unlike GPA and MPA, where kidney involvement is a central feature, nephropathy is not considered a prominent aspect in patients with EGPA.1,3 For this reason, the nephrologist is not usually regarded as a key player in the care of EGPA patients. The case reported here dispels this misconception by demonstrating that, in selected cases, nephrological expertise may play an active role in patient management.