IgA antineutrophil cytoplasmic antibodies in cutaneous vasculitis

Background Antineutrophil cytoplasmic antibodies (ANCA) of the IgA isotype have, for the most part, been detected in patients with Henoch-Schonlein purpura (HSP) or inflammatory bowel disease. Objectives We have evaluated the prevalence of IgA ANCA in a series of patients with different causes of cutaneous vasculitis. Methods Forty consecutive patients with histologically proven leucocytoclastic vasculitis were included in the study: 18 had systemic vasculitis as well as cutaneous lesions, 10 of whom were diagnosed as having HSP, and 22 had only cutaneous vasculitis (with no identified cause in 10 cases). IgA ANCA were sought by indirect immunofluorescence using ethanol-fixed human neutrophil preparations as the substrate. Results IgA ANCA were detected in six of 40 patients (15%) (one each with HSP, ulcerative colitis, Sjogren's syndrome, hypergammaglobulinaemia associated with Castelman's disease, erythema elevatum diutinum and bacterial endocarditis). Three of these patients also had IgG ANCA whose target antigen remained unidentified. Conclusions IgA ANCA are rarely observed in HSP (10%) and can be detected in a wide variety of other cutaneous vasculitides.