Nivolumab-induced Myocarditis Successfully Treated with Corticosteroid Therapy: A Case Report and Review of the Literature

Matsuo, Keisuke; Ishiguro, Takashi; Najama, Takatomo; Shimizu, Yoshihiko; Kobayashi, Yasuhito; Mutou, Makoto

We performed a myocardial biopsy from the endocardial side of the left ventricle. The biopsy revealed fibrosis of the myocardial tissue, infiltration of inflammatory cells, and T cell-dominant lymphocyte infiltration, which were consistent with lymphocytic myocarditis (Fig. 3 ). Viral PCR testing using myocardial specimens for influenza virus, adenovirus, respiratory syncytial virus, corona virus, parainfluenza virus, bocavirus, echovirus, coxsackie virus echovirus, and enterovirus were all negative. Serum antibodies measured in the convalescent phase against echovirus, coxsackie virus, enterovirus, adenovirus, influenza virus, parainfluenza virus, and respiratory syncytial virus were not increased compared with those measured in the acute phase. We subsequently considered nivolumab-induced myocarditis. We also detected transient complete atrioventricular block during the myocardial biopsy and inserted a temporary pacemaker. Because of these new findings, we diagnosed the patient with nivolumab-induced myocarditis and started administration of methylprednisolone 1 g daily for 3 days.