Toripalimab is a monoclonal antibody targeting programmed cell death protein 1 
(PD-1). It has recently been approved as an immune checkpoint inhibitor in 
second-line therapies in patients with unresectable or metastatic melanoma; 
however, it may be associated with various immune-related adverse events 
(irAEs). Here we report a case of toripalimab-induced dermatomyositis in a 
patient receiving treatment for metastatic melanoma. The symptoms were relieved 
by discontinuing toripalimab and administering once-daily intravenous 
methylprednisolone 1 mg/kg. We suggest that this case serves a warning to 
clinicians of the need to be aware of the possiblilty of toripalimab-induced 
dermatomyositis. Early recognition and treatment may prevent progression and 
improve prognosis of this irAE.