Intravesical bacillus Calmette-Guerin (BCG)
therapy is an effective and safe
immunotherapy for superficial
bladder cancer. However,
reactive arthritis (ReA) is reported as an adverse event in about 0.5-1% of patients receiving intravesical BCG
therapy. ReA is known as a kind of spondyloarthritis, the main pathological finding of which is enthesitis. Here we report a patient with ReA induced by intravesical BCG
therapy for
bladder cancer, in whom the diagnosis of ReA was supported by ultrasonographic findings of enthesitis and
synovitis. A 69-year-old male was diagnosed with
carcinoma in situ of the bladder and treated with intravesical BCG
therapy. After the third intravesical BCG injection,
pain and swelling appeared in both wrists. Ultrasonographic examination revealed not only intra-articular
synovitis in the bilateral wrist joint, wrist flexor
tenosynovitis, and wrist extensor
tenosynovitis, but also enthesitis of the flexor carpi radialis tendon (FCR). The severe enthesitis of the FCR in both wrists was considered to be an important finding that supported the diagnosis in this patient. Thus, we diagnosed this case as ReA induced by intravesical BCG
therapy. In clinical practice, ReA is often difficult to distinguish from seronegative
rheumatoid arthritis and other
rheumatic diseases. Ultrasonographic findings of enthesitis may support a definitive diagnosis for these patients.