Aseptic Meningitis as an Immune-Related Adverse Eventafter Pembrolizumab

he management of patients with advanced malignancies is challenging, although recent advances withimmunotherapy have shown better outcomes. Pembrolizumab has been associated with a variety of immune-related side effects,but the occurrence of aseptic meningitis is rare.Case. A 55-year-old male with a history of metastatic lung adenocarcinomapreviously treated with pembrolizumab presented with persistent severe headaches and photophobia. Subsequent workup withcerebrospinalfluid analysis showed elevated opening pressure, increased nucleated cells with 30% lymphocytes, elevated proteinlevels, and normal glucose levels. The patient was started on high doses of IV steroids and progressed with significantimprovement of his symptoms.Discussion. Given the rarity of this side effect, this case is a reminder that immune checkpointinhibitors can cause aseptic meningitis and its early recognition is important for initiation of therapy with steroids and promptdiscontinuation of the immunotherapy agent.