We describe a case of LC identified at the initial diagnosis of AML consistent with therapy-related disease in a patient with metastatic non-small-cell lung cancer (NSCLC) previously treated with cytotoxic chemotherapy and immunotherapy.<h4>Case presentation</h4>A 78-year-old woman with Stage IV NSCLC (adenocarcinoma, no actionable mutations, PD-L1 negative) initially received carboplatin, pemetrexed, and pembrolizumab, complicated by neutropenic fever. The gene discussed is CD274; the disease is acute myeloid leukemia.