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IntroductionHuman leukocyte antigen B27 (HLA-B27) is considered as a risk factor for development of juvenile idiopathic arthritis (JIA).The aim of this study was to analyse the prevalence of HLA-B27 antigen in JIA categories and its influence on disease onset and response to conventional therapy.Material and methodsThe retrospective analysis included 461 unselected children with JIA hospitalized in a single reference rheumatology centre between July 2007 and June 2012. The diagnosis was based on criteria by the International League of Association for Rheumatology. HLA-B27 was determined in 387 of all patients (84%) by hybridization of the amplified, labelled product to immobilize it on the microarray probe.ResultsHLA-B27 antigen was found in 104 of 383 affected children (27.2%), 48 of 206 girls (23.3%), and 56 of 177 boys (31.6%) – most frequently in patients with enthesitis-related arthritis (71%), psoriatic arthritis (50%) and unclassified cases (86.7%). The age of JIA onset was slightly (by 1 year) but significantly different in patients with and without HLA-B27 antigen [11 (8.5–14) vs. 10 (5–13.5) years.; p < 0.001].The use of disease-modifying antirheumatic drugs (DMARDs) and corticosteroids was more frequently clinically ineffective in HLA-B27 positive than negative patients (23.1% vs. 15.2%; p = 0.09). Patients with polyarthritis, systemic, and psoriatic arthritis more frequently received biological therapy. HLA-B27 positive patients with enthesitis-related arthritis received biological therapy more frequently than HLA-B27 negative ones (20.4% vs. 0, respectively; p = 0.09).ConclusionsHLA-B27 antigen is a strong risk factor for the development of enthesitis-related arthritis, and to a lesser extent for psoriatic arthritis and extended course of oligoarthritis. The presence of this antigen does not affect the disease onset but seems to predict resistance to therapy with disease-modifying drugs and corticosteroids.

Pachydermodactyly (PDD) is a rare and benign form of digital soft tissues fibromatosis, which affects the skin of the fingers. The disorder is characterized by asymptomatic, symmetric, progressive soft tissue swelling of the proximal interphalangeal (PIP) joints of the fingers. The etiology of disease remains unknown. It is usually acquired, even though there are some publications that document family cases. It affects mainly adolescent men.We report two boys with the bilateral swelling of the of the PIP joints of the fingers and skin and subcutaneous tissue thickening. Based on clinical manifestations, radiological study and histopathological examination, pachydermodactyly was diagnosed.PDD is a rare and benign disorder, although it is important to consider other diseases, especially rheumatic conditions, in the differential diagnosis in order to avoid unnecessary additional tests and treatments.

BackgroundThe usefulness of musculoskeletal ultrasonography (MSUS) in paediatric population is limited by lack of reference values. One of such parameters is hip joint capsule thickness, postulated as an early measure for synovitis. However, the joint capsule is hardly a distinguished structure from slit synovial cavity in patients with little or no fluid collection. Therefore, in patients without effusion, it is more convenient to measure hip joint capsule thickness together with synovial cavity.The aim of the study was to establish percentile chart for hip joint capsule and synovial cavity thickness (HJC&SCT) in apparently healthy children.Material and methodsThe analysis included 816 US of hip joint in 408 children without musculoskeletal disorders, distributed equally throughout the whole developmental period in 18 one-year subgroups. Hip joints US was performed according to standard protocol including measurement of HJC&SCT in a single rheumatology centre by three investigators.ResultsThe 3rd, 10th, 25th, 50th, 75th, 90th, and 97th HJC&SCT percentile curves were depicted in the age and height charts for the combined group of girls and boys. The median HJC&SCT values were increasing with age from 3.7 (C10 - C90: 3.3 – 4.2) mm in the first year of life up to 6.7 (5.8 – 7.3) in 16 years old, and above. In a similar way the increase was seen with height from 3.9 (3.5 – 4.7) mm in shorter than 95 cm to 6.9 (6.2 – 7.4) mm in taller than 169 cm subjects. Intra-observer and inter-observer mean precision was less than 1.8 and 12.5%, respectively.ConclusionThe developed centile chart for hip joint capsule and synovial cavity thickness in the paediatric population is expected to improve detection of hip joint capsule disorders, including synovitis in juvenile idiopathic arthritis.

ObjectivesMethotrexate (MTX) is one of the most frequently used, highly effective disease-modifying drugs in juvenile idiopathic arthritis (JIA) therapy. The drug can be administered orally or subcutaneously, but the efficacy and tolerance of these two routes of administration raise doubts in JIA patients. The aim of the study was to evaluate MTX efficacy and tolerability after switching from the oral to the subcutaneous route of administration in children with JIA.Material and methodsA single-centre, questionnaire-based assessment of MTX efficacy and tolerance in 126 unselected JIA patients with longer than 6 months of follow-up was performed. In all patients, MTX was initially administered orally. The response to MTX treatment was analysed according to American College of Rheumatology (ACR) paediatric criteria.ResultsSix-month MTX therapy was effective (ACR score ≥ 30) in 83 children (65.9%). The oral route of MTX administration was changed to subcutaneous in 32 patients after a mean period of 14 months due to intolerance (n = 20) or reluctance to take the oral formulation (n = 12). This group of children was significantly younger (p = 0.02) but did not differ from the group of children that continued oral treatment in other aspects, including MTX dose.Six months after switching from oral to subcutaneous MTX the ACR score remained unchanged. Three children (9.4%) still reported symptoms of drug intolerance.ConclusionsThe switch from oral to subcutaneous MTX may increase the response rate in JIA patients with intolerance of its oral formulation. The reluctance to take oral MTX can be anticipated in early childhood, and should be considered in the individualization of therapy, having also in mind the lower risk of severe gastrointestinal adverse drug reactions.