# Sarcoid‐Like Reaction (SLR) Associated With Immune Checkpoint Inhibitors in Metastatic Renal Cell Carcinoma

## TL;DR

This paper reports the first case of a sarcoid-like reaction in the kidney of a patient treated with immune checkpoint inhibitors for metastatic renal cell carcinoma.

## Contribution

The study presents the first documented case of SLR in the kidney following ICI treatment for renal cell carcinoma.

## Key findings

- A 71-year-old woman developed non-caseating epithelioid cell granulomas in her kidney after ICI therapy.
- The granulomas were diagnosed as sarcoid-like reaction, not systemic sarcoidosis.
- This case highlights the importance of distinguishing SLR from cancer progression in ICI-treated patients.

## Abstract

Immune checkpoint inhibitors (ICIs) are useful in the treatment of metastatic renal cell carcinoma. ICIs have been associated with a variety of immune‐related adverse events (irAEs), one of which is a sarcoid‐like reaction (SLR). SLR is often difficult to distinguish from cancer progression.

The patient is a 71‐year‐old woman. She underwent laparoscopic nephrectomy after 4 courses of ipilimumab + nivolumab therapy for clear cell renal cell carcinoma with femoral bone metastasis. In the pathological examination, in addition to tumor‐infiltrating lymphocytes, numerous non‐caseating epithelioid cell granulomas were found in the tumor. The occurrence of non‐caseating epithelioid cell granuloma in a patient who did not meet the diagnostic criteria for systemic sarcoidosis was considered SLR due to ICI.

We report the first case of a patient who underwent surgery for metastatic renal cell carcinoma after treatment with ICI and who was pathologically diagnosed with SLR in the kidney.