Neuromuscular associated respiratory failure is a rare toxicity of immunotherapy for malignant tumors. In most cases, it may overlap with the symptoms of the primary disease or myocarditis, myositis and myasthenia gravis, resulting in difficult etiological diagnosis. Early detection and optimal treatment are still topics that need attention. Here, a case of 51-year-old male lung cancer patient with sintilimab-associated myasthenia gravis, myositis, and myocarditis overlap syndrome involving the diaphragm who developed severe type II respiratory failure was reported. After high-dose methylprednisolone, immunoglobulin and pyridostigmine intravenous injection with non-invasive positive pressure ventilation, the patient's symptoms improved significantly and was discharged. One year later, the patient received immunotherapy again due to tumor progression. After 53 days, he developed dyspnea again. Chest X-ray demonstrated marked elevation of the diaphragm, and the electromyogram demonstrated dysfunction of diaphragm. With rapid diagnosis and timely treatment, the patient was finally discharged safely. A comprehensive search of PubMed, EMBASE was performed to identify all previously reported cases of immune checkpoint inhibitors-associated respiratory failure. The potential mechanisms of respiratory failure caused by ICI-associated diaphragmatic dysfunction may be related to T cell-mediated immune disturbances and we proposed possible diagnostic processes. For patients with unexplained respiratory failure who are receiving immunotherapy, standardized diagnostic strategies should be implemented immediately on admission before deciding whether to conduct a more invasive diagnostic procedure or empirical treatment.
Keywords: Immune-related adverse events; case report; diaphragmatic dysfunction; myositis; respiratory failure.