Immunofluorescence co-staining of myeloperoxidase and subnucleosomal complex was performed on lesional skin samples from patients with Schnitzler's syndrome, other neutrophilic dermatoses (cryopyrin-associated periodic syndrome, Sweet syndrome, and pyoderma gangrenosum), urticarial vasculitis and chronic spontaneous urticaria as well as healthy control skin. This evidence concerns the gene MPO and sweet syndrome.