Patient was an 85-year-old female with recurrent squamous cell carcinoma of the vulva status post 2 cycles of Pembrolizumab. During a 3-week period, she developed progressive dysphagia, double vision, neck weakness and general malaise. Other reported symptoms were headache and urinary incontinence. The patient reported to the Emergency Department and was subsequently admitted to the Neurological ICU. Neurological exam showed neck extensor and flexor muscle weakness, diplopia, mild diplopia, and generalized weakness.

Brain MRI (Magnetic Resonance Imaging) showed no brainstem pathology. Lumbar Puncture showed (2 Nucleated cells), (81 glucose) and (38 protein). Serum MG antibodies (LRP4, AchR, MusK) were negative. Single-fiber EMG was consistent with neuromuscular junction disorder, most consistent with Myasthenia Gravis. Chest CT (Computed Tomography) was negative. Treatment included IVIG, prednisone, pyridostigmine, methotrexate, and plasmapheresis. Diplopia and neck musculature weakness improved. Due to her chronic medical conditions, the patient and family opted for hospice care.

With rising interest in novel immunotherapies for cancer treatment, reporting on significant side effects becomes essential. There are few case reports on checkpoint inhibitor related Myasthenia Gravis. This case aims to provide knowledge on diagnostic and management strategies with patients that present with similar clinical findings to improve future patient care.