Lambert-Eaton Myasthenic Syndrome Recurrence Induced by Pembrolizumab in a Patient with Non-small-cell Lung Cancer

Intern Med. 2023 Apr 1;62(7):1055-1058. doi: 10.2169/internalmedicine.0072-22. Epub 2022 Aug 30.


A 73-year-old woman in complete remission from localized small-cell lung cancer associated with Lambert-Eaton myasthenic syndrome (LEMS) 22 years earlier was referred to our hospital and diagnosed with non-small-cell lung cancer. After three courses of pembrolizumab, an immune checkpoint inhibitor, the patient complained of muscle weakness, fatigue, ptosis, and dysarthria. The anti-voltage-gated calcium channel antibody level was elevated, and waxing was observed on a high-frequency repetitive stimulation test using an electromyogram. We diagnosed her with recurrence of LEMS as an immune-related adverse event (irAE) induced by pembrolizumab. After intravenous immunoglobulin therapy, the patient's symptoms improved, and she was discharged.

Keywords: Lambert-Eaton myasthenic syndrome; immune checkpoint inhibitor; immune-related adverse event; non-small-cell lung cancer.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Carcinoma, Non-Small-Cell Lung* / complications
  • Carcinoma, Non-Small-Cell Lung* / drug therapy
  • Female
  • Humans
  • Lambert-Eaton Myasthenic Syndrome* / chemically induced
  • Lambert-Eaton Myasthenic Syndrome* / diagnosis
  • Lambert-Eaton Myasthenic Syndrome* / drug therapy
  • Lung Neoplasms* / complications
  • Small Cell Lung Carcinoma* / complications


  • pembrolizumab