TY - JOUR T1 - 447 Systemic juvenile idiopathic arthritis without arthritis as the cause of intermittent persistent fever in a 7-year old girl JF - Archives of Disease in Childhood JO - Arch Dis Child SP - A187 LP - A187 DO - 10.1136/archdischild-2021-europaediatrics.447 VL - 106 IS - Suppl 2 AU - Ana Smajo AU - Vana Vukić AU - Lovro Lamot Y1 - 2021/10/01 UR - http://adc.bmj.com/content/106/Suppl_2/A187.1.abstract N2 - Background Intermittent fever along with increased inflammatory markers (CRP and ESR) most commonly is the sign of an infectious disease. Nevertheless, without an adequate response to antibiotic treatment, it should raise concern of other conditions, including several rheumatic, like Kawasaki disease, periodic fever syndromes and systemic form of juvenile idiopathic arthritis (JIA), even when no clear arthritis is present.Case Presentation We present a case of a 7-year-old girl with a 14-month history of intermittent fever with increased inflammatory markers, along with unspecific symptoms such as hepatomegaly, polymorphous rash and migratory arthralgia. An extensive diagnostic workup excluded infectious aetiology, genetic testing did not detect pathogenic mutations. Despite the treatment with intravenous imunoglobulines and low dose glucocorticoids (GCs), the fever did not subside. Finally, extensive laboratory workup revealed increased proinflammatory cytokines IL-6 and TNF-alpha along with chronic anaemia and thrombocytosis. The systemic subtype of JIA was considered, and treatment with pulse (30mg/kg), continued with high (2mg/kg) doses of GCs was initiated with an instant resolution of symptoms. Nevertheless, after the weaning of GCs, the new exacerbation was observed and therefore tocilizumab, humanized monoclonal antibody against IL-6 receptor, was initiated.Conclusion Systemic form of juvenile idiopathic arthritis is a heterogeneous disease dominated musculoskeletal and systemic symptoms. While the former ones are a result of similar pathophysiologiocal mechanisms as other forms of JIA, activation of the nonspecific immune response is responsible for the sytemic ones, similar to other autoinflammatory diseases. Therefore, it is possible that in some cases of systemic form of JIA, systemic inflammation is present without the musculoskeletal symptoms. With the existing classification criteria of the International League against rheumatism (ILAR) it can be difficult to diagnose and initiate appropriate therapy. Consequently it can mislead to recognize a serious complication – macrophage activation the syndrome. The recognition of the unique nature of systemic JIA in comparison to other types of JIA as well as an increased understanding of its pathogenesis, provides a better outcome and prognosis for children who often go undiagnosed with a debilitating chronic condition. ER -