Cytokine Release Syndrome: A Case Report.

Although generally well tolerated, immune checkpoint inhibitors can occasionally lead to severe immune-related adverse events, including cytokine release syndrome (CRS), a condition resulting from excessive immune activation and cytokine secretion, specifically interleukin-6 (IL-6). We report the case of a 71-year-old male with stage IVB lung adenocarcinoma undergoing maintenance therapy with pembrolizumab and pemetrexed, who presented with an acute confusional state and fever unresponsive to antipyretics. An extensive infectious, neurological, and oncological workup was negative. Elevated serum IL-6 levels (270 pg/mL) supported the diagnosis of CRS. The patient was successfully treated with systemic corticosteroids, resulting in the resolution of fever and neurological symptoms. This case underscores the importance of early recognition and prompt management of CRS in patients receiving immune checkpoint inhibitors, highlighting corticosteroid therapy as an effective treatment strategy.