Track: Case Reports

Abstract:

Eosinophilic granulomatosis with polyangiitis (EGPA) is an ANCA-associated vasculitis that presents with asthma, peripheral eosinophilia, and involvement of several organ systems. We describe a patient with a new diagnosis of ANCA-negative EGPA after several months of arthritis, myalgias, and peripheral eosinophilia. Skin examination showed crusted pinpoint papules in the axillae along with circumferential purpuric plaques studded with vesicles on the wrists. Histopathology of the lesions demonstrated two distinct patterns in the axilla and wrist, respectively: eosinophilic cellulitis and eosinophilic eccrine hidradenitis surmounted by eosinophilic crusts. Neither vasculitis nor granulomas were seen. While EGPA is historically associated with p-ANCA, it is now recognized that p-ANCA is positive in only 30% of patients. Furthermore, while cutaneous lesions of EGPA classically demonstrate leukocytoclastic vasculitis with palisading granulomas and necrotic eosinophils, these findings are less commonly seen in patients who are ANCA negative. Instead, those with negative ANCA may demonstrate eosinophilic tissue infiltration, including in the skin. Our ANCA-negative patient illustrates this phenomenon, with absence of cutaneous vasculitis or granulomas and instead presence of eosinophilic tissue infiltration in two distinct patterns, including the first report of eosinophilic hidradenitis occurring in EGPA.

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Zachary Thornton