[IgG paraproteinemia and arthritis. Description of a clinical case].

The case is reported of a patient with monoclonal gammopathy of undetermined significance (M.G.U.S.) in whom suddenly an acute polyarthritis appeared. Upon differential diagnosis, this arthropathy was attributed to the precipitation of paraprotein-containing complexes within the synovial fluid leading to an inflammatory articular reaction. Treatment with low doses of methylprednisolone lead to complete remission of this arthritis.