Myasthenia Gravis Associated With Pembrolizumab for Relapsed Lung Cancer After Thymoma Resection

Immunotherapy has demonstrated clinical efficacy in patients with thymic epithelial tumors; however, there is the potential risk of serious immune-related adverse events (irAEs). Here, we report a case of myasthenia gravis (MG) associated with pembrolizumab treatment that developed after thymoma resection in a patient with lung adenocarcinoma. Symptoms of MG occurred 16 days after pembrolizumab administration and progressed rapidly, necessitating mechanical ventilation and tracheostomy. Even after tumor resection, careful monitoring is crucial for patients with thymic tumors being managed with immune checkpoint therapy, particularly regarding the development of severe irAEs.