Arthritis and Tenosynovitis Associated With the Anti-PD1 Antibody Pembrolizumab in Metastatic Melanoma

We report the acute onset of polyarticular inflammatory arthritis in 2 patients receiving the immune check-point inhibitor, pembrolizumab (MK-3475), anti-PD1 drug for metastatic melanoma after 14 and 11 months therapy, respectively. The first patient had severe tenosynovitis, synovitis, bone marrow edema, and myositis, whereas the second patient had predominantly synovitis and tenosynovitis. Good symptomatic control was obtained with...