IgA nephropathy in a patient with systemic lupus erythematosus.

Systemic lupus erythematosus is generally recognized to be a multisystem autoimmune disease with kidney involvement. However, the occurrence of other non-lupus glomerulopathies has been rarely reported in patients with systemic lupus erythematosus. It is well known that lupus nephritis may switch over time to another class according to the World Health Organization classification. It seems likely that IgA nephropathy is a clinical characteristic of a particular subset of patients with systemic lupus erythematosus. We report a 22-year-old Japanese man with recurrence of proteinuria. The renal flare occurred when he was without lupus clinical and serological activity, and renal remission was only obtained with angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker therapy. Although the incidence of IgA nephropathy is high in Japan, we believe that this is the first report of a Japanese patient in which lupus nephritis switched over time to IgA nephropathy.