LAUSR

A 10-year-old Han Chinese girl was initially referred to the Department of Nephrology at the Children’s Hospital Zhejiang University School of Medicine in September 2018 for edema around the eyes and the lower extremities for 10 days. Ten days prior, her parents noticed that she had periorbital edema and then lower extremity edema. She also had oliguria and foamy urine. She had no fever or cough, no jaundice, and no chest pain or chest distress. She had gained 2 kg over the previous 10 days. The family history was previously negative for kidney disease. The patient was living with her parents and 1-month-old brother. Physical examination revealed that the patient’s temperature was 36.3 °C, heart rate was 98 beats/min, and blood pressure was 112/72 mmHg. There was overt facial and pedal pitting edema. Laboratory investigations (with a normal range given in parentheses) included the following: urinalysis revealed 3+ protein; spot protein: creatinine ratio on first morning urine, 15.96 mg/ mg Cr (< 0.2 mg/mg Cr); serum albumin, 17.6 g/L (32–52 g/L); serum creatinine, 38μmol/L (15–77μmol/L); serum cholesterol, 9.12 mmol/L (3–5.7 mmol/L); 24-h urine protein excretion, 4596.8 mg/24 h (< 150mg/24 h); and complete blood cell count, within normal limits. Other investigations included anti-nuclear antibody (ANA), negative; anti-double-stranded DNA, negative; anti-neutrophil cytoplasmic antibodies (ANCAs), negative; complement components C3 and C4, within normal limits; and hepatitis B and C virus and human immunodeficiency virus (HIV), negative. The results of cranial magnetic resonance and electroencephalogram were normal. Bilateral renal magnetic resonance was also normal. Interestingly, her father also found himself with newonset ankle swelling when his daughter was hospitalized, and membranous nephropathy, Ehrenreich-Churg stage I, and hypertension stage III were diagnosed 1 week later. Given the specific etiology of this patient, a kidney biopsy was performed. Light microscopy showed normal glomerular volume, good capillary loops, normal glomerular structure, no glomerular adhesions or crescent formation, slightly tubular degeneration, and very little interstitial inflammatory cell infiltration. Immunofluorescence microscopy showed no deposition of IgG, IgA, C3, C4, or Fib, and IgM was diffuse in glomeruli. There was no abnormal distribution of type IV collagens a2 and a5. Electron microscopy showed that the foot process fused extensively, the basement membrane was approximately 300 nm thick, the mesangium was slightly proliferated, and no electrondense deposits were found in glomeruli. Immunofluorescence microscopy was negative (Fig. 1).