Limb arteriolar vasculitis induced by pembrolizumab plus chemotherapy in a patient with lung cancer

Immune-related adverse events (irAEs) associated with immune checkpoint inhibitors are becoming more common; however, irAEs involving blood vessels are rare. We report a patient with limb arteriolar vasculitis induced by pembrolizumab plus chemotherapy. He was 60-year-old man who received first-line treatment with pembrolizumab plus chemotherapy for postoperative lung cancer recurrence. Two weeks after the first administration, he experienced Raynaud's phenomenon. We initiated a vasodilator, but his symptoms worsened, and we considered an irAE. We initiated oral prednisolone, and his symptoms gradually improved. A few weeks later, we performed skin biopsies of both of the patient's feet, and pathological examination revealed arteriolar thrombosis with slight perivascular lymphocytic infiltration. Infiltration of neutrophils with karyorrhexis in the subendothelium was also seen. He also developed acute kidney injury, likely owing to thrombosis. Physical examination of bilateral fingers and toes in patients with lung cancer should be performed carefully after administering pembrolizumab therapy.