Immune checkpoint-mediated myositis and myasthenia gravis: A case report and review of evaluation and management.

BACKGROUND

We present a case of myositis and possible overlapping neuromuscular junction disorder following treatment with nivolumab for recurrent/metastatic head and neck squamous cell carcinoma (HNSCC).

METHODS

We report a 75-year-old man with recurrent stage IVA, T1N2cM0 oral cavity HNSCC treated with weight-dosed nivolumab who presented three weeks later with severe fatigue, generalized weakness, and bilateral ptosis. Evaluation demonstrated elevated creatine kinase and myopathic motor units on electromyography, supporting a diagnosis of an underlying muscle disease. Elevated serum acetylcholine receptor binding antibodies raised the possibility of concurrent myasthenia gravis.

RESULTS

He received corticosteroids and plasmapheresis without improvement in muscle weakness. His course was complicated by bacteremia, cardiac arrest, and concerns for recurrent malignancy. Following a two-month hospital stay, he was made comfort care and died.

CONCLUSIONS

With increasing usage of checkpoint inhibitors in HNSCC, clinicians must be aware of and vigilant for associated rare but serious adverse events.