Bicipital synovial cyst as the sole musculoskeletal presentation of systemic juvenile idiopathic arthritis-case report.

To describe a unique presentation of fever and bilateral bicipital synovial cysts in young female with systemic juvenile idiopathic arthritis (SJIA). A previous healthy 5-year-old female presented with spiking fever and sudden painless bilateral swelling on the flexor aspect of the upper arm. Ultrasonography confirmed a cystic structure with multiple septae, thickening and tenosynovitis of bicipital tendon but without Doppler signals inside or shoulder synovitis, enlightens the term of non-articular synovitis. Thorough analysis of clinical manifestations, disease assessment measures, laboratory findings and imaging of arm swellings eventually disclosed unusual case of SJIA. Systemic juvenile idiopathic arthritis should be considered in case of spiking fever with bicipital synovial cysts. Ultrasound is a useful diagnostic tool in this condition.