Eosinophilic Fasciitis following Checkpoint Inhibitor Therapy with Pembrolizumab.

With the increasing number of indications for checkpoint inhibitor therapy in cancer patients, rheumatology specialists are often involved in the diagnosis and management of immune-related adverse events (irAEs). The most common rheumatic irAEs are arthritis, sicca syndrome, polymyalgia rheumatica, and myositis. Eosinophilic fasciitis, an already rare rheumatic disease, is a very unusual rheumatic irAE. Eosinophilic fasciitis, whether idiopathic or checkpoint inhibitor-associated, has very particular clinical symptoms and findings, such as the orange peel skin appearance and the Groove sign, which the physicians need to be aware of and recognise timely in order to diminish morbidity.