Systemic-Onset Juvenile Idiopathic Arthritis – aka Still’s, Systemic Juvenile Idiopathic Arthritis

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Acronym:
soJIA/sJIA

SAID group:
Macrophage Activation Diseases

Gene:
Currently unknown for most cases. LACC1 noted in some patients. [100] HLA-DRB1 in some patients with European ancestry. [57] Genetic testing in research only at this time.

Inheritance:
Complex

Ethnicity:
Affects all races. soJIA accounts for 10% of all JIA. [45]

Frequency:
Uncommon. 0.4–0.9 cases per 100,000 people, per year. [46]

Timing of symptoms:
Fevers often > 39°C 1-2 times/day for >2 weeks, most often occurring in the evening with arthralgia, rash and other symptoms. [45] [46]

Age of onset:
Onset before the age of 16–most often by 2 years of age, or between 0-5 yrs. of age. [46]

Skin cutaneous:
Rash: Fleeting, evanescent, migratory, bright salmon-pink, morbilliform, macular rash that often presents with the onset of fevers. [45] [46]

Neurologic:
High fevers >39°C 1-2 times/day for >2 weeks. Other neurological symptoms are rare. A few cases with seizures, meningismus, irritability and decreased level of consciousness. [46]

Auditory:
Not noted to be from soJIA. [45] [46]

Ophthalamic:
Uveitis can be a complication from soJIA. [46]

Cardiopulmonary:
Serositis (especially pericarditis) is often seen. Pleuritis (pleurisy), pleural effusions can occur. Some with pulmonary disease. Risk for Macrophage Activation Syndrome (MAS). [46]

Abdominal:
Peritonitis rarely occurs. 50% have an splenomegaly, some with hepatomegaly. [46]

Lymphatic:
Many with generalized lymphadenopathy. Some with mesenteric adenitis. Half with splenomegaly. [45] [46]

Joints bones muscles cartilage:
Arthralgias may come before the arthritis. 88% have polyarticular or oligoarticular arthritis, most often in the wrists, knees, and/or ankles. Some with cervical spine, hip, temporomandibular joint arthritis or synovial cysts. [45] [46]

Vasculitis:
Not noted. [45] [46]

Amyloidosis:
Amyloidosis occurs in 7.4% of patients in the USA, and 16% in Turkey. [46]

Abnormal labs:
High: ESR, CRP, WBC, SAA, ferritin, aldolase, IL-18. Elevated liver function tests (LFT’s). Leukocytosis, thrombocytosis. Anemia is common. [45] [46]

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