Background Large synovial cysts are rarely seen in juvenile idiopathic arthritis. When they do appear, they usually appear in the popliteal space (Baker's cyst). Less commonly, they occur in the antecubital area or as bicipital synovial cysts. Bicipital synovial cysts present as a sudden-onset painless swelling on the flexor aspect of the proximal upper arm. This type of synovial cyst has been described as a complication to systemic onset JIA (sJIA). Patients usually have active disease when the cysts develop and most cysts resolve with the medical treatment for arthritis. In some cases the cysts reappear, coinciding with a relapse of sJIA. The diagnosis of bicipital synovial cysts may be confirmed by ultrasonography.
Objectives To investigate if the number of sJIA patients presenting with bicipital synovial cysts has changed over time.
Methods A retrospective analysis of the medical records of patients diagnosed with sJIA according to ILAR criteria, admitted to our clinic from February 1998 to December 2014. A total of 77 patients were found. Selected were the five who presented with bicipital synovial cysts. For each patient the following data were noted: the number and dates of episodes with bicipital synovial cysts and the disease duration prior to the first episode, active joint count, extra-articular manifestations, history of medical treatment and if there had been any episodes of other unusual synovial cysts.
Results The first patient to present with bicipital synovial cysts in our cohort did so in 1999. The fifth patient had onset of the cyst type in 2006. Since 2006, no new patient has presented with bicipital synovial cysts in our clinic, nor have any of the five patients experienced a relapse of the cyst type. Each patient experienced between two and seven episodes of bicipital synovial cysts.
In general the patients had active disease with elevated sedimentation rate and acute phase reactants (CRP), fever, rash and arthritis when presenting with the bicipital synovial cysts. All patients had polyarticular course of sJIA. The median age at onset of sJIA was 3.75 years (range 2.75– 7.33 years). The median disease duration prior to the first episode with bicipital synovial cyst was 10 months (range: 2 to 16 months). One of the five patients also presented with Baker's cysts.
At the patients' first episode of bicipital synovial cysts, four had received prednisolone between two and eleven months prior (initial dosage 1-1.5 mg/kg, followed by an attempt to taper off the dose). Two of these patients were also in methotrexate (MTX) treatment. None of the patients had received anti-IL1 nor anti-IL-6 biologics. The remaining patient presented with the cyst at the diagnosis of sJIA and thus had received no prior treatment.
Conclusions Bicipital synovial cysts should always be considered if a child presents with relevant symptoms and they are easily detected by ultrasonography. However, they no longer seem a significant clinical challenge in our clinic. This is based on the marked drop in number of new patients presenting with the cyst type. As well as the considerable time since a patient has experienced a relapse of the cyst. Is the change in frequency of bicipital synovial cysts an expression of better disease control of sJIA?
Disclosure of Interest None declared