Overlapping Juvenile Idiopathic Arthritis and Systemic Lupus Erythematosus: A Case Report

Juvenile idiopathic arthritis (JIA) is a chronic rheumatic disease that affects children and adolescents. Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of antinuclear antibodies (ANA). The coexistence of two or more autoimmune diseases in a single patient varies in frequency but remains relatively rare. A 12-year-old boy was diagnosed with systemic JIA overlapping SLE. The patient presented with intermittent fever accompanied by joint pain. The antinuclear antibody indirect immunofluorescence (ANA-IF) examination showed a homogeneous pattern with a titer of 1:10,000. The International League of Associations for Rheumatology (ILAR) criteria for systemic JIA require arthritis accompanied by or preceded by documented daily fever for a minimum duration of two weeks, with or without an evanescent rash. SLE classification criteria utilizing ANA as an entry criterion demonstrate that an ANA titer of ≥1:80 has a sensitivity of 98%. A diagnosis of SLE can be established if at least one clinical criterion is present and the total score reaches ≥10 points. In this case, the patient exhibited a homogeneous ANA pattern with a titer of 1:10,000. Clinical criteria included fever, leukopenia, and joint involvement, along with an immunological criterion of low C3 levels, resulting in a total score of 15, thus fulfilling the classification criteria for SLE. A 12-year-old boy with systemic JIA overlapping with SLE presented with complaints of fever and joint pain. The ILAR criteria supported the diagnosis of systemic JIA, while the 2019 ACR/EULAR criteria confirmed the diagnosis of SLE.