Lupus anticoagulant in myasthenia gravis associated with IgM gammopathy

The plasma of a patient with myasthenia gravis had strong lupus anticoagula nt activity and his IgM paraprotein displayed non-specific inhibition to co agulation factors LX, XI, XII, prekallikrein, and high molecular weight kin inogen. He was placed on prednisolone, which resulted in improvement in his myasthenic symptoms, but the prolongation of APTT and macroglobulinemia re mained. Double filtration plasmapheresis successfully decreased the serum I gM level from 1,190 mg/dl to 375 mg/dl and APTT improved from 58 s to 38 s. Myasthenia gravis is frequently associated with other autoimmune diseases, but the association with lupus anticoagulant and IgM gammopathy is rare.