Association of ankylosing spondylitis with IgA-multiple myeloma: report of a case and pathogenetic considerations.

Multiple myeloma has rarely been reported in patients with ankylosing spondylitis. We observed a patient with a 20-year history of ankylosing spondylitis, who subsequently developed IgA myeloma. This association may not be simply coincidental. It has been proposed that the protracted stimulation of immunocytes by inflammatory lesions on the mucosal surfaces of the gastrointestinal, respiratory, and biliary tracts, where lymphocytes are already committed to IgA production, may be implicated in the pathogenesis of IgA myeloma in some patients. Ankylosing spondylitis is a chronic inflammatory disease, probably resulting from the interaction of a genetic predisposition involving HLA-B27 with an environmental event such as enteric bacterial infection. We propose that ankylosing spondylitis and IgA myeloma occurring concomitantly in our patient implies a possible pathogenetic relationship. In ankylosing spondylitis, persistent reticuloendothelial stimulation, due to chronic subclinical gastrointestinal infection, may lead to IgA-producing plasma cell activation and proliferation, and subsequent IgA myeloma development.