A 4-year-old girl with a history of eczema and absence seizures treated with ethosuximide presented with persistent fever, migratory joint pain, joint swelling, and hematuria. She was last at her baseline state of health 3 months prior to presentation, after which she experienced recurrent fevers and was hospitalized three times for pneumonia and impetigo. She then developed arthralgia, joint swelling, abdominal pain, fever, sore throat, cough, and change in behavior, prompting admission to a referring hospital. She was diagnosed with acute otitis media, started on ciprofloxacin, and transferred to our hospital for further management.
At admission, her temperature was 37.5 C, heart rate was 115 beats/min, respiratory rate was 20 breaths/min, and blood pressure was 121/84 mmHg. She appeared uncomfortable and was "not herself" according to her mother. Physical examination revealed diffuse polyarthritis and tender generalized lymphadenopathy. There were no appreciable skin rashes, mucosal changes, cardiac murmurs, or pleurodynia. She did not have any history of travel outside the United States, toxic exposures, or contact with other sick children. Family history was significant for SLE in her paternal grandmother's sister. There was no family history of consanguinity.
Admission laboratory studies were significant for anemia (hemoglobin 10.5 g/dL, range: 11.5-14.5 g/dL), elevated erythrocyte sedimentation rate (ESR; >145 mm/h, range: 0-20 mm/h), elevated C-reactive protein (1.12 mg/dL, range: 0.0-0.9 mg/dL), and a positive Direct Coombs test. White blood cell count (9.1 x 103/microL, range: 4.0-12 x 103/microL), platelets (267 x 103/microL, range: 150-450 x 103/microL), and thyroid-stimulating hormone (1.34 UIU/mL, range: 0.66-4.75 UIU/mL) were within normal limits. HIV and tuberculosis testing were negative. Urinalysis was notable for 30 mg/dL of protein as well as 15 red blood cells per high-power field. Quantitative urine protein-to-creatinine ratio was 1790 mg/g (nephrotic range > 3500 mg/g).   The calcium-to-creatinine ratio was 0.07 (normal range <0.2).   There was no microbial growth on urine cultures. Creatine kinase was within normal limits. Serum complement studies were notable for low C3 (48 mg/dL, range: 86-166) and low C4 (6 mg/dL, range: 9.7-36). C1q immune complex binding protein was high (61 mcg Eq/mL, range <= 25). She was also positive for both lupus anticoagulant and anticardiolipin antibodies. Recent outpatient rheumatology labs revealed an ESR of 77 mm/h, elevated antinuclear antibodies (ANA; >1:1280), as well as positive anti-double-stranded DNA (dsDNA), anti-Smith and anti-ribonucleoprotein antibodies. Unfortunately, her symptoms worsened before she could follow up on these results in clinic.
Brain magnetic resonance imaging (MRI) with arterial and venous phase contrast was done due to abnormal behavior; no intracranial pathology or vascular abnormalities were present. Abdominal ultrasound revealed grade 2 pelviectasis in both kidneys, mild distension of the right renal pelvis, slight hepatomegaly, increased mesenteric echogenicity, trace pelvic free fluid, and no masses.   A bone marrow biopsy:performed due to her arthralgias and lymphadenopathy:showed mildly hypocellular bone marrow with no blasts or other pathology. To further investigate the hematuria and proteinuria, a kidney biopsy was done, which revealed mild mesangial hypercellularity and immune complex membranous glomerulonephritis with full house IgM/C3-dominant staining on immunofluorescence and reticular aggregates on electron microscopy, consistent with Membranous Lupus Nephritis Class V (Figure 1).