Multinucleated podocytes as a clue to diagnosis of juvenile nephropathic cystinosis.

BACKGROUND  : Cystinosis is a rare autosomal recessive lysosomal disorder that mainly affects the kidney and eye. Early treatment with cysteamine significantly improves the prognosis. However, early diagnosis of cystinosis, especially the juvenile nephropathic form, remains challenging because typical symptoms only become apparent in adulthood. We herein describe a 13-year-old girl who presented with proteinuria only but was diagnosed with juvenile nephropathic cystinosis based on multinucleated podocytes in her kidney biopsy specimen. We also studied the nephropathology of another case to determine the features of the multinucleated podocytes. CASE DIAGNOSIS: A previously healthy 13-year-old girl presented to our hospital because proteinuria had been detected in her school urine screening. She had been noted to have proteinuria on her school urine screening when she was 11 years of age but there was no consultation with her physician at that time. She was asymptomatic and had no other abnormalities on examination other than a relatively high urinary ß-2 microglobulin level. Her kidney biopsy showed 15 multinucleated podocytes in 34 glomeruli, and the mean number of nuclei per multinucleated podocyte was 4.4. Ophthalmological examination showed cystine crystals in her cornea. Her white blood cell cystine level was high, and she was diagnosed with juvenile nephropathic cystinosis. She started oral cysteamine treatment and showed almost no progression of the disease after 2 years. In another patient with juvenile nephropathic cystinosis, there were 25 multinucleated podocytes in 63 glomeruli, and the mean number of nuclei per multinucleated podocyte was 2.9. CONCLUSION: Early diagnosis is crucial to improve the prognosis of patients with cystinosis. This report emphasizes the importance of recognizing the unique pathological feature of multinucleated podocytes as an essential clue to the diagnosis of cystinosis.

Half of children with IgA vasculitis-associated nephritis with nephrotic state spontaneously recover.

BACKGROUND: The clinical spectrum of Henoch-Schönlein purpura nephritis (HSPN), now known as IgA vasculitis-associated nephritis (IgAVN), ranges from isolated microscopic haematuria to nephrotic syndrome, progressive glomerulonephritis, and kidney failure. The outcome also varies, and the management of IgAVN is controversial. The presence of nephrotic state at disease onset is thought to be a risk factor of a poor prognosis. However, not all patients with nephrotic state have a poor prognosis, and it is unclear whether they need early treatment. METHODS: We herein retrospectively examined the clinical course of paediatric IgAVN cases with nephrotic state (serum albumin [sAlb]<3.0 g/dL and urine protein-creatinine ratio of >2.0 g/ gCr) without kidney injury treated at our hospital between 2010 and 2018. RESULTS: Of the 216 patients with IgAVN identified, 17 met the inclusion criteria. The median follow-up period from disease onset to the last observation was 40.5 months (IQR:31.0-74.2). Eleven patients were male, the median age at onset was 5 years, the minimum serum Alb level was 1.9 g/dL, the maximum proteinuria value was 12.3 g/gCr, and the median minimum eGFR was 86.0 mL/min/1.73 m2 in the acute phase. Eight patients (47%) achieved resolution of nephrotic state within 3 months and complete remission without treatment by the last observation. The patients with spontaneous resolution of nephrotic state had less severe hypoalbuminaemia (Alb<2.0 g/dL) and tended to show a quick increase in the serum albumin level. CONCLUSIONS: Our study found that half of paediatric patients with IgAVN with nephrotic state achieved spontaneous resolution without treatment and enjoyed a favourable short-term outcome. Consideration of the duration of nephrotic state and trends in the serum albumin level in children with IgAVN may allow unnecessary kidney biopsies and immunosuppressive therapy to be avoided.