# PD-1/PD-L1 checkpoint inhibitor-induced encephalitis in patients with lung adenocarcinoma: a report of three cases

## TL;DR

This paper reports three cases of encephalitis in lung cancer patients treated with PD-1/PD-L1 inhibitors, emphasizing the importance of timely diagnosis and treatment.

## Contribution

The novelty lies in presenting three rare cases of ICI-induced encephalitis and highlighting diagnostic challenges.

## Key findings

- All three patients experienced loss of consciousness and responded well to steroid treatment.
- Encephalitis diagnosis is difficult based solely on clinical symptoms and requires ruling out infections.
- Survival improved with timely management despite the severity of symptoms.

## Abstract

Immune checkpoint inhibitor (ICI)-induced encephalitis is rare. We present three cases of encephalitis associated with ICIs in lung adenocarcinoma patients. These patients presented with a variety of symptoms, but one of the common symptoms for all patients was loss of consciousness. All patients responded well to steroid treatment and survived longer than one month after the onset of symptoms. These cases highlight the difficulties in diagnosing encephalitis based only on clinical information, and timely management is important to improve survival. Opportunistic infections also have to be ruled out to diagnose ICI-induced encephalitis especially when brain metastases co-exist.