PDCD1 and metastatic melanoma: Each recurrence was carefully followed-up with extended resection and scheduled treatment using ICIs, nivolumab (anti-PD-1 antibody) 80 mg, and ipilimumab (anti-CTLA-4 antibody) 3 mg/kg intravenously every 3 weeks for a total of 4 doses for aggravated metastatic malignant melanoma.