Systemic Juvenile Idiopathic Arthritis (sJIA)

Systemic Juvenile Idiopathic Arthritis (sJIA) is a type of arthritis that affects children and involves inflammation throughout the whole body. It primarily impacts the joints, causing pain, swelling, and stiffness, but also causes symptoms like fever, rash, and fatigue. This condition affects the immune system, which mistakenly attacks the body's own tissues. The inflammation can lead to difficulty moving and performing daily activities. Because it involves multiple body systems, it can sometimes cause serious complications affecting the heart, liver, or lungs.

Systemic Juvenile Idiopathic Arthritis (sJIA) is a subtype of juvenile idiopathic arthritis characterized by systemic inflammation and arthritis in children under 16 years old. It involves an autoinflammatory process driven by dysregulated innate immunity, with elevated cytokines such as IL-1, IL-6, and IL-18 playing a central role. Clinically, sJIA presents with quotidian fever spikes, an evanescent salmon-pink rash, and arthritis affecting multiple joints. The disease can cause hepatosplenomegaly, lymphadenopathy, and serositis. It is distinguished from other JIA subtypes by its systemic features and risk of life-threatening complications like macrophage activation syndrome (MAS). Diagnosis requires exclusion of infections, malignancies, and other rheumatologic diseases.