Successful treatment of a patient with rheumatoid arthritis and IgA-κ multiple myeloma with tocilizumab.

A 63-year-old woman receiving tumor necrosis factor (TNF) inhibitors for rheumatoid arthritis (RA) was found to have smoldering IgA-kappa type multiple myeloma (MM). Retrospective examination of stored serum samples revealed a steady increase of serum IgA levels after the start of TNF inhibitor therapy. The patient's articular symptoms showed marked exacerbation when TNF inhibitors were discontinued because of fear of worsening the MM. Tocilizumab improved RA symptoms dramatically and stabilized serum IgA levels for 13 months after a transient steep rise. This case suggests that tocilizumab can be used safely in patients with inflammatory disorders with coexisting MM.