Musculoskeletal ultrasound in the management of immune checkpoint inhibitor arthritis

Immune checkpoint inhibitors (ICIs) have transformed cancer care, but their use is frequently complicated by immune-related adverse events (irAEs), including rheumatic manifestations such as arthritis. Distinguishing between inflammatory and non-inflammatory musculoskeletal symptoms is challenging, yet critical for appropriate management. Musculoskeletal ultrasound (MSKUS) provides unique advantages in this context by enabling the detection of subclinical synovitis, periarticular pathology, and crystal deposition, while also facilitating treatment decisions, including targeted corticosteroid injections. We present four cases that highlight the utility of MSKUS as a frontline tool in the evaluation of musculoskeletal irAEs.