[Development of myasthenia gravis after thymectomy for thymoma]

Impaired neuromuscular transmission in myasthenia gravis is caused by autoimmune mechanisms. The association of myasthenia gravis with pathological abnormalities of the thymus has been known for a long time and was the reason why thymectomy was used in the treatment of myasthenia gravis before the immunocompetent impact of the thymus and the autoimmune pathogenesis of myasthenia was known. Forms of myasthenia refractory to thymectomy, and in particular the development of myasthenia gravis after thymectomy on account of a thymoma, indicate the fact that in case of destruction of postsynaptic acetylcholine receptors an important part is played by extrathymic humoral and cellular autoimmune mechanisms. In the submitted paper the authors describe three patients where myasthenia gravis was manifested several months to 14 years after thymectomy on account of a thymoma. The presented facts emphasize the importance of immunosuppressive treatment of patients with myasthenia gravis.