Pembrolizumab is known to cause specific immune-related adverse events (irAE), and myocarditis is a rare but serious irAE. For head and neck cancer, there has been only one case in the KEYNOTE-048 trial pembrolizumab combination group, with no detailed report. We report a case of myocarditis as a pembrolizumab irAE in a patient with late cervical lymph node metastasis from tongue cancer. A 90-year-old man underwent a partial glossectomy (excisional biopsy) in July 2019 following a diagnosis of right-sided tongue cancer, and histopathological diagnosis confirmed a well-differentiated squamous cell carcinoma. Imaging studies performed in January 2020 revealed metastatic lymphadenopathy of the right cervical level IIA nodes. Pembrolizumab therapy was initiated in February 2020 due to the patient’s refusal of the recommended surgery. Although the patient did not initially experience any adverse events, he developed generalized muscle weakness 21 days after administration of the second dose. Blood test results, electrocardiography and coronary artery computed tomography revealed irAE-related myocarditis. He underwent long-term prednisolone therapy for myocarditis. Although his creatine kinase and troponin T levels decreased with electrocardiographic evidence of the gradual resolution of the myocarditis, the patient’s daily life activity significantly declined during hospitalization. He was subsequently transferred to a long-term care hospital for best supportive care.
In administering ICIs, it was considered extremely important to share knowledge on the management of irAE and to establish medical collaboration systems for early detection and treatment.
