Tenosynovitis induced by an immune checkpoint inhibitor: A case report and literature review

Abstract

A 51-year-old man underwent second-line treatment for non-small-cell lung cancer (NSCLC) with the immune checkpoint inhibitor (ICI) pembrolizumab. On day 2 after two cycles of pembrolizumab, he presented with edema limited to the left third, fourth, and fifth fingers. Based on symptoms, laboratory results, and contrast-enhanced magnetic resonance imaging (MRI) findings, we diagnosed him with tenosynovitis. We prescribed oral prednisolone (0.5 mg/kg/day), and pembrolizumab was continued. Prednisolone immediately relieved the symptoms, and the tumor was still shrinking on day 21 after eight cycles of pembrolizumab. ICIinduced tenosynovitis was managed while continuing ICI usage, suggesting that 0.5 mg/kg/day prednisone might be effective for tenosynovitis without ICI cessation.