# Fatal early-onset checkpoint inhibitor pneumonitis in a patient with advanced squamous-cell lung cancer with underlying pulmonary fibrosis: a case report and review of the literature

## TL;DR

A patient with lung cancer and fibrotic lung disease died after a single dose of immunotherapy due to severe lung inflammation.

## Contribution

This case highlights the rare but fatal risk of checkpoint inhibitor pneumonitis in patients with fibrotic interstitial lung disease.

## Key findings

- Fulminant early-onset checkpoint inhibitor pneumonitis occurred after a single dose of pembrolizumab in a patient with fibrotic ILD.
- The patient's condition deteriorated despite immunosuppressive treatment and died within 27 days.
- The case underscores the need for cautious treatment and monitoring in patients with fibrotic ILD receiving immunotherapy.

## Abstract

We report a case of fulminant checkpoint inhibitor pneumonitis (CIP) occurring after a single dose of immune checkpoint inhibitor (ICI) therapy in a patient with advanced non-small cell lung cancer and underlying fibrotic interstitial lung disease (ILD), illustrating a rare but clinically significant and often fatal immune-related adverse event.

A 78-year-old woman with stage IVb squamous-cell carcinoma of the lung and idiopathic pulmonary fibrosis (IPF) developed progressive dyspnea, hypoxemia, and systemic inflammation shortly after receiving her first dose of pembrolizumab. High-resolution computed tomography (HRCT) revealed new bilateral ground-glass opacities superimposed on a fibrotic background with a definite usual interstitial pneumonia (UIP) pattern.

Fulminant early-onset CIP was diagnosed after exclusion of infectious causes. Despite discontinuation of immunotherapy and escalation of immunosuppressive treatment—including high-dose corticosteroids, mycophenolate mofetil, and infliximab—the patient’s respiratory status deteriorated, resulting in death 27 days after treatment initiation.

This case illustrates that life-threatening CIP can occur after a single dose of ICI in patients with fibrotic ILD. It emphasizes the urgent need for risk-adapted treatment strategies and enhanced monitoring protocols in this high-risk population.