Isolated testicular vasculitis due to immune checkpoint inhibitor.

Immune checkpoint inhibitors are increasingly being used to treat various malignancies; consequently, more rheumatological side effects, ranging from arthritis to vasculitis, are being reported. Here we present, for the first time, a case of vasculitis involving the testicle in the setting of an immune checkpoint inhibitor. As reported in previous cases, recurrence of a malignancy, as opposed to vasculitis, was initially suspected, thus creating a diagnostic dilemma. These rheumatological side effects have garnered attention as they potentially provide a window into in the pathogenesis of rheumatological diseases.