# Case Report: Successful treatment of pulmonary lymphomatoid granulomatosis with a PD-1 inhibitor-based regimen

## TL;DR

A patient with a rare aggressive lung tumor survived 52 months using a PD-1 inhibitor treatment, offering a new potential therapy.

## Contribution

This is the first reported case of successful PD-1 inhibitor-based treatment for pulmonary lymphomatoid granulomatosis.

## Key findings

- A PD-1 inhibitor regimen achieved 52 months of survival without disease progression in a PLG patient.
- The patient exhibited PD-1, PD-L1, and p53 expression, which may inform treatment selection for similar cases.
- The case suggests PD-1 inhibitors could be a promising new treatment strategy for PLG.

## Abstract

Pulmonary lymphomatoid granulomatosis (PLG) is a rare and aggressively progressive tumor characterized by atypical clinical manifestations and pathological features. This condition is highly prone to misdiagnosis and underdiagnosis. The absence of standardized treatment regimens has resulted in diverse recommendations in the literature, predominantly favoring rituximab-based therapies. However, the prognosis for these patients remains poor, with a median survival time of only 14 months. Recently, we encountered a case of PLG exhibiting programmed cell death-1 (PD-1), PD-L1, and p53 expression. The patient was treated with a PD-1 inhibitor-based regimen. Remarkably, the patient achieved an overall survival (OS) of 52 months at the most recent follow-up, without disease progression. This case stands as a notable observation, particularly because the utilization of a PD-1 inhibitor-based regimen has not been previously reported for PLG treatment. We hope this case will contribute significantly to enhancing physicians’ understanding of PLG and provide a new potential treatment strategy.