A 3.5-year-old girl was diagnosed with hyperuricemia at her birth. At the age of 6 months, she developed red rash(mild scaly)in face, trunk and extremities and was recorded by a dermatologist. Her skin lesions were treated with topical corticosteroids. At 1 year of age, she developed skin cysts of different sizes in the bilateral wrist and ankle joints. At the age of 3, she was hospitalized because of pain in the left calf and red eyes.
Rheumatological examination showed numerous brown ichthyosis rash covered the face, trunk and extremities. Subcutaneous nodules were found over the affected joints of wrists and ankles. Ophthalmological examination showed signs of uveitis, keratitis and trichiasis.
Blood examination revealed a white blood cell count of 11230/µL (normal: 4000–12000) and C-reactive protein level of 4.21 mg/L (normal: less than 8). The serum immunoglobulin level was elevated. The immunoglobulin G (IgG) level was elevated to 1620 mg/dL (normal: 500–1060 ), IgA level was 150 mg/dl (normal:34-138), IgM level was 236 mg/dl (normal:44-144), and IgE level was 101 000mg/dl(normal:0-10000. The serum uric acid was elevated to 600umol/L(normal:155-357), 24 hours of sodium (45mmol/24h, normal: 130-260), phosphorus (317.7mg/24h, normal:400-1300), chlorine (53mmol/24h, normal:170-250), and uric acid (865umol/24h, normal:1480-4430) in the urine were decreased. Antinuclear antibody was borderline. Autoantibodies, including anti-dsDNA and anti-cyclic citrullinated peptide, were negative.
Computed tomography (CT) suggested bilateral axillary lymph node enlargement but lung and hilar lymph nodes were negative. Magnetic Resonance Imaging(MRI) showed abnormal signal in bilateral wrist and ankles with bone cysts of right calcaneus bone marrow cavity. B-scan ultrasonography showed vitreous opacity. The whole exome sequencing showed a heterozygous variant in gene NOD2: c.1001G>T(p.R334L). Neither of her parents had the NOD2 mutation.
She was diagnosed with sporadic BS according to her clinical presentation and gene mutaion. Furthermore, we suspected that she has renal excretion dysfunction, but whether it is caused by NOD2 mutation was unknown.
She received the treatment of prednisolone (0.45mg/kg/d) combined with adalimumab (20mg biweekly) and methotrexate(6.25mg/week). She was also given febuxostat to lower uric acid levels. The comprehensive therapy was efficacy, the number of cysts was decreased and ocular damage was not progressed. For the first time, her serum uric acid decreased to normal levels after 2 weeks with oral febuxostat tablet.