Case Presentation: A 66-year-old female with metastatic small cell lung cancer involving brain, liver, and bones was admitted via ED with generalized weakness, mild confusion, and decreased oral intake for 3 days. She was initiated on immunotherapy with immune checkpoint inhibitors, ipilimumab (human cytotoxic T-lymphocyte antigen 4 (CTLA-4)-blocking antibody) and nivolumab (a programmed death receptor-1 [...]