Successful treatment of MuSK antibody-positive myasthenia gravis with rituximab.

We report on a 56-year-old woman with muscle-specific receptor tyrosine kinase (MuSK) antibody-positive myasthenia with predominant bulbar symptoms and respiratory insufficiency. Conventional immunosuppression (prednisolone, azathioprine, mycophenolate mofetil) could not maintain the clinical improvement initially achieved by repeated plasma exchanges. Therefore, treatment with rituximab was initiated. After 2 months of rituximab treatment, remarkable clinical improvement correlating with a reduction of MuSK serum antibodies was seen. The patient continued to remain stable 12 months after initiation of therapy. This case report demonstrates that rituximab may be an effective and tolerable treatment in MuSK antibody-positive myasthenia gravis.