Spectrum of cutaneous vasculitis in eosinophilic granulomatosis with polyangiitis (Churg-Strauss): a case series.

Background: The diverse histopathologic spectrum of cutaneous vasculitis in eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss syndrome) has not been well described.

Methods: Fifteen skin biopsy specimens from 9 EGPA patients with histopathologically proven necrotizing vasculitis were reviewed clinicopathologically.

Results: Among 8 patients with dermal small vessel vasculitis, neutrophilic vasculitis was observed in 2 myeloperoxidase (MPO)-antineutrophil cytoplasmic antibodies (ANCA)-positive patients, whereas the remaining 6 MPO-ANCA-negative patients showed eosinophilic vasculitis in 3 and a mixed infiltrate of neutrophils and eosinophils in another 3 patients. Five patients with muscular vessel vasculitis showed vasculitis at different inflammatory stages in separate or coexisting at the same biopsied skin lesions: acute stage (eosinophilic vasculitis), granulomatous stage (granulomatous vasculitis), and healed stage. Coexistent small vessel and muscular vessel vasculitis was found in 4 patients.

Conclusions: The histopathologic spectrum of dermal small vessel vasculitis in EGPA ranges from eosinophilic vasculitis with negative MPO-ANCA at one end to neutrophilic vasculitis with positive MPO-ANCA at the other end. The affected vessels ranging from dermal small vessels to subcutaneous muscular vessels in addition to the MPO-ANCA phenotype may account for the many facets of vasculitis in EGPA.