Objective:

To illustrate a structured clinical approach for diagnosing and managing immune checkpoint inhibitor (ICI)-associated aseptic meningitis in lung cancer patients.

Approach:

• Case 1: A 66-year-old woman developed symptoms of fever, neck stiffness, and altered mental status 13 days after starting atezolizumab. CSF analysis showed pleocytosis and protein elevation. After excluding other diagnoses, she received high-dose intravenous methylprednisolone, resulting in prompt improvement.
• Case 2: A 75-year-old man experienced colitis followed by grade 3 meningitis after receiving durvalumab and tremelimumab. CSF analysis and further tests excluded infections and leptomeningeal carcinomatosis, allowing for timely immunosuppression.

Key Findings:

• ICI-associated aseptic meningitis is a rare but serious adverse event that requires prompt diagnosis and treatment.
• High-dose corticosteroids are effective as initial therapy for suspected ICI-associated aseptic meningitis.
• CSF multiplex PCR can aid in excluding common infections during the diagnostic process.

Interpretation:

The cases highlight the importance of rapid exclusion of alternative diagnoses and a stepwise approach to immunosuppressive treatment in suspected ICI-associated aseptic meningitis.

Limitations:

• The cases are limited to two patients, which may not represent the broader population.
• The effectiveness of adjunctive treatments like tocilizumab in refractory cases requires further investigation.

Conclusion:

These cases illustrate a practical clinical approach to managing suspected ICI-associated aseptic meningitis, emphasizing the need for timely intervention and careful diagnostic evaluation.