Clinical aspects of HLA-B27 positive enthesitis-related arthritis in childhood

Abstract

Introduction: Enthesitis-related arthritis (ERA) is a form of juvenile idiopathic arthritis (JIA) according to the International League Against Rheumatism (ILAR) classification. Enthesitis-related arthritis accounts for 8.6 to 18.9% of all children with JIA. The first clinical sign of ERA is usually asymmetrical arthritis of large joints, especially of the lower extremities. Axial involvement is typically presented by unilateral or bilateral sacroiliitis. Enthesopathy is a unique feature of ERA. Aim: The aim of this study is to determine the most common clinical characteristics in children with HLA-B27 positive ERA. Materials and Methods: We performed a retrospective analysis of 55 patients up to 16 years of age, diagnosed with HLA-B27 positive ERA. We used physical and laboratory tests as well as imaging techniques to assess various clinical aspects of ERA in every patient. Results: Demographic characteristics showed prevalence of male gender—44 boys vs. 11 girls (4:1 ratio). The mean age of onset was 13.3 years for boys and 9.9 years for girls. The most commonly affected joints were as follows: knees in 49% of the cases, ankles—in 43.6%, hip joints—in 36.3%, intertarsal/metatarsophalangeal joints—in 20%. Physical examination found enthesitis in 24 of the patients (43.6%). The most commonly affected entheses were: the site of attachment of the Achilles tendon in 66.6% of the cases, the site of attachment of the plantar fascia in 45.8%, the site of attachment of the patellar tendon in 12.5%. Plain X-ray of the sacroiliac joints detected sacroiliitis in 34 of the patients (61.8%). In over 90% of the cases, the sacroiliitis was bilateral. Conclusion: HLA-B27 positive ERA is a rare pathology in childhood. This study confirms typical epidemiological and clinical characteristics of the disease among Bulgarian children.