Pediatric Granulomatous Arthritis (PGA) – aka Juvenile Systemic Granulomatosis, Blau syndrome, Early Onset Sarcoidosis, or Jabs Syndrome
Granulomatous, Increased NF-kB Signalling
NOD2 (certain mutations)
Affects all races.
Unknown, but rare.
Timing of symptoms:
Intermittent or persistent daily fevers, rash and arthritis.
Age of onset:
Rash often develops by 4 months of age, fevers and other symptoms present by 4 years of age. 
First symptom: scaly plaques. The rash often starts on the face, then on the torso or chest. Biopsies with non-caseating granulomatous dermatitis. 
Intermittent-persistent daily fevers. Some have cranial neuropathies. 80% have vision damage and joint deformities if untreated. Some cases have peripheral nerves affected. 
Not noted. 
Uveitis (some with blindness). 50% with cataracts, 1:3 patients get secondary glaucoma. Inflamed conjunctiva (conjunctivitis), and/or inflammation of the lacrimal glands, retina and optic nerves is common. 
Joints bones muscles cartilage:
Symmetrical chronic polyarthritis or oligoarthritis of the wrists, knees, ankles with a boggy appearance is usually caused by an exuberant tenosynovitis.   
Some with vasculitis, leukocytoclastic vasculitis. 
Not noted. 
High CRP and ESR, angiotensin converting enzyme (ACE), immunoglobulins. Anemia, leukopenia, eosinophilia, hematuria, proteinuria, pyuria, abnormal liver function tests (LFTs).  
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Glass 2nd, D. A., Maender, J., & Metry, D. (2009). Two pediatric cases of Blau syndrome. Dermatol Online J, 15(5). Retrieved from http://dermatology.cdlib.org/1512/articles/blau/glass.html