IgA myeloma presenting as Henoch-Schonlein purpura with nephritis

IgA nephropathy (IgAN) and Henoch-Schonlein purpura (HSP) are both characte rized by IgA-mediated tissue injury, including mesangial proliferative glom erulonephritis. Abnormalities of IgA1 glycosylation are described in IgA ne phropathy and HSP nephritis. IgA-antineutrophil cytoplasmic antibodies (ANC A) have been inconsistently described In the serum of patients with HSP. In IgA myeloma, the paraprotein-mediated renal lesion is typically cast nephr opathy; IgAN or HSP have only rarely been reported in myeloma even when an IgA paraprotein is circulating in large concentrations. We report the case of a 50-year-old man with IgA myeloma who presented with HSP including neph ritis and rapidly progressive renal failure. His IgA1 had altered O-glycosy lation in the pattern seen in IgAN and also contained an IgA-ANCA. This cas e adds further weight to the evidence that IgA1 O-glycosylation abnormaliti es predispose to mesangial IgA deposition and also that IgA-ANCA may have a pathogenic role in the development of HSP. (C) 2000 by the National Kidney Foundation, Inc.