Myasthenia Gravis and Myocarditis After Administration of Pembrolizumab in a Patient With Metastatic Non-small Cell Lung Cancer and Resected Thymoma

•This case report highlights that patients with resected thymoma are still at increased risk of immune-related adverse events and a careful discussion of the benefits and risks of immune checkpoint inhibitors (ICI) treatment is warranted.•Presence of autoantibodies pre-ICI may be predictive of a higher risk of immune-related adverse events as compared to patients who are seronegative.•There may be a role to screen for autoantibodies pre-ICI for risk stratification.