Waldenström's macroglobulinemia and myasthenia gravis.

Until now, three patients with IgG and only one with IgM class monoclonal gammopathy (without the classical features of Waldenström's macroglobulinemia) have been reported in subjects with myasthenia gravis. A case of Waldenström's macroglobulinemia which occurred before thymectomy in a myasthenic patient is described in this paper. Both neuromuscular disease and the lymphocyte dyscrasia worsened after operation and before starting steroid treatment. No evidence of circulating immune complexes nor of anti-acetylcholine receptor antibodies belonging to the IgM class was found. The patient's HLA type shared A2 and B15 antigens with an IgG-lambda monoclonal gammopathy previously reported in a myasthenic woman, and his genotype included the Bw15 specificity which has been described to be frequent in Waldenström's macroglobulinemia. It appears that a persistent thymic abnormality, responsible for myasthenia gravis, may be associated with a lymphoreticular neoplasm.