Mithu Maheswaranathan, MD; Michel G. Khouri, MD; Sophia C. Weinmann, MD
A 47-year-old man with melanoma presented with 1 week of low-grade fevers, myalgias, elevated creatine kinase levels, and proximal muscle weakness. He previously underwent amputation of a finger and began adjuvant nivolumab for stage IIIC melanoma. One week later, he developed fevers, myalgias, dark urine, weakness, and difficulty walking. What is the diagnosis and what would you do next?