Potential utility of anti‐TNF drugs in synovial chondromatosis associated with ankylosing spondylitis

We describe a previously unreported association of ankylosing spondylitis with synovial chondromatosis, and briefly review previously reported cases and treatment of synovial chondromatosis in patients with other immune‐mediated inflammatory arthritides. A 20‐year‐old man with ankylosing spondylitis whose axial disease was in remission with nonsteroidal anti‐inflammatory drugs and oral disease‐modifying anti‐rheumatic drugs developed recurrent right knee pain and swelling. Magnetic resonance imaging of his right knee revealed calcified loose bodies, suggestive of synovial chondromatosis. While waiting for the surgical intervention and other invasive therapy previously reported in patients with synovial chondromatosis, a trial of etanercept eliminated the pain and swelling of the knee; however, the loose bodies have persisted during the 2‐year follow‐up. Thus, synovial chondromatosis should be considered in the differential diagnoses of a refractory monoarticular pain and swelling in patients with otherwise controlled inflammatory arthritis. Our report advocates a trial of anti‐tumor necrosis factor drugs, which might delay the need for invasive therapy in patients with synovial chondromatosis.