What is the role of thymectomy in the treatment of myasthenia gravis (MG)?

Updated: Aug 27, 2018
  • Author: Abbas A Jowkar, MBBS; Chief Editor: Nicholas Lorenzo, MD, CPE, MHCM, FAAPL  more...
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Thymic abnormalities are common in patients with MG. Of patients with generalized MG, 85% have thymic hyperplasia, and 10-15% have thymoma. Thymic pathology in early-onset generalized MG is invariably thymic hyperplasia. These patients invariably are anti-AChR-ab positive. 

There is evidence that resident cells in the thymus, including myoid cells and epithelial cells, express various subunits of AChR, including the α subunit. Additional factors found uniquely in hyperplastic MG thymus include increased expression of chemokines that attract immigrant CD4+ T and B cells; the presence of nAChR-reactive B and CD4+ T cells and anti-AChR antibody-secreting plasma cells; cytokines that can facilitate B cell activation, differentiation, and survival; and possibly decreased CD4+ CD25+ regulatory T cell function. [57]

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