Serum complement C3 and C4 levels were in the normal range, and serological markers for systemic vasculitis (antinuclear antibodies, ANA; extractable nuclear antigen antibodies, ENA; antineutrophil cytoplasmic antibodies, ANCA; cryoglobulins) were negative in all patients, except for ANA (grainy speckled pattern, titer 1:640), detected in patient 3 with anti-Ro/SSA positivity (titer 1:480); as this patient had no symptom of Sjögren’s disease, lip biopsy for minor salivary gland was not performed. Here, C4A is linked to necrotizing vasculitis.