A case of myasthenia gravis associated with thymoma, multiple schwannomas and monoclonal IgA gammopathy.

Myasthenia gravis, malignant thymoma, multiple schwannomas and monoclonal IgA gammopathy coexisted in a 54-year-old Japanese man. Serum acetylcholine receptor antibody activity was located in the IgG fraction, but not in the paraprotein peak. It was speculated that all these disorders might fall under the spectrum of the diseases associated with thymic abnormality or that some growth factors might induce neoplasms and activation of B cell clones of autoantibodies (including acetylcholine receptor antibody) in this case.