# Surgical Management of Destructive Thyroiditis Triggered by Neoadjuvant Immune Checkpoint Inhibitor Therapy in Locally Advanced Non-Small Cell Lung Cancer: A Case Report

## TL;DR

A patient with lung cancer developed thyroiditis from immune therapy and required steroid treatment before surgery.

## Contribution

This case report highlights the management of destructive thyroiditis caused by neoadjuvant immune checkpoint inhibitors before lung cancer surgery.

## Key findings

- Destructive thyroiditis due to immune-related adverse events was diagnosed before surgery.
- Steroid treatment improved thyroid function, allowing safe surgical resection.
- Routine thyroid function tests are recommended for patients receiving preoperative immune checkpoint inhibitors.

## Abstract

The use of immune checkpoint inhibitors (ICIs) as neoadjuvant therapies for locally advanced and resectable non-small cell lung cancer is increasing. As a result, immune-related adverse events (irAEs) may be observed before surgery and may require preoperative intervention. We report the case of a patient with destructive thyroiditis induced by neoadjuvant ICI treatment, in which surgical resection was performed after steroid treatment.

A 74-year-old woman was diagnosed with slow-growing squamous cell carcinoma of the right upper lobe during treatment for another disease. Imaging studies revealed a small nodule suggestive of pulmonary metastasis in the right upper lobe and hilar lymph node metastasis. The patient was initially diagnosed with primary lung cancer of the right upper lobe (cT3N1M0, Stage IIIA, TNM Classification, 8th edition), and neoadjuvant nivolumab combined with chemotherapy was planned every 3 weeks for three cycles. After the first cycle, the patient experienced drug-induced kidney injury. Nivolumab and chemotherapy were discontinued, and surgical resection was planned. However, a laboratory analysis on the day before surgery revealed elevated free triiodothyronine and free thyroxine, and decreased thyroid-stimulating hormone. Subsequent examination led to a diagnosis of destructive thyroiditis due to irAEs, and surgery was postponed. Dexamethasone was administered orally for 1 week, and once the thyroid function showed consistent improvement, a thoracoscopic right upper lobectomy was performed. The patient progressed without any other complications after surgery.

This report highlights a case of preoperative destructive thyroiditis secondary to irAEs. In patients receiving preoperative ICIs therapy, routine blood tests, including thyroid function tests, are recommended as part of preoperative assessment. In this case, the patient underwent lobectomy safely following steroid administration. The optimal timing of surgery in patients with preoperative ICI-induced destructive thyroiditis requires further investigation.