Programmed cell death protein-1 inhibitor–induced granuloma annulare and hypertrophic lichen planus masquerading as squamous cell carcinoma

Abstract

Pembrolizumab is a humanized monoclonal antibody against programmed cell death protein-1 (PD-1) and is an effective treatment for advanced non–small cell lung cancer1 and advanced melanoma.2 PD-1 functions as a checkpoint of the effector stage of the immune system and inactivates T cells when they reach tumors.2