# A Case Report of Hemophagocytic Lymphohistiocytosis and Meningitis Due to Atezolizumab Treatment for Lung Adenocarcinoma

## TL;DR

An 80-year-old man developed life-threatening immune-related side effects, including hemophagocytic lymphohistiocytosis and meningitis, after receiving atezolizumab for lung cancer.

## Contribution

This is the first reported case of atezolizumab-induced hemophagocytic lymphohistiocytosis with meningitis.

## Key findings

- Hemophagocytic lymphohistiocytosis and meningitis occurred in a patient treated with atezolizumab for lung adenocarcinoma.
- Both conditions improved with continued oral prednisolone treatment.
- Early diagnosis and treatment of rare immune-related adverse events are crucial.

## Abstract

Immune checkpoint inhibitors (ICIs) are used to treat a variety of tumors. Despite their broad beneficial effects, these inhibitors can cause immune-related adverse events (irAEs) and even death. Hemophagocytic lymphohistiocytosis (HLH) and meningitis, although infrequent, can be aggressive and life-threatening due to excessive immune activation. Herein, we report a case of an 80-year-old man who developed HLH after receiving atezolizumab monotherapy as a second-line treatment for lung adenocarcinoma. He was treated for HLH with oral prednisolone (PSL), but further ataxia and dysuria developed, and a lumbar puncture diagnosed meningitis. Both HLH and meningitis improved with continued oral PSL treatment. This is the first case of atezolizumab-induced HLH with meningitis and highlights the importance of early diagnosis and treatment for rare irAE.