To review the clinical features of brachial synovial cyst.
A case of bilateral brachial synovial cysts is described in a child suffering from systemic juvenile idiopathic arthritis during a relapse. Magnetic resonance imaging and ultrasonography were conducted to further evaluate the nature of the cysts. The case is compared with known cases in a literature review.
Review of the literature showed that brachial synovial cysts occur most commonly in systemic juvenile idiopathic arthritis. It is considered that uncontrolled systemic inflammation and recurrent disease activity might be the cause of synovial cysts.
Brachial synovial cyst is a rare manifestation of juvenile idiopathic arthritis. Uncontrolled systemic inflammation inducing chronic damage to joint structure may be the primary cause of synovial cyst formation.