Persistent Immature Glomeruli in a Girl with Refractory Nephrotic Syndrome

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We recently observed an 8-year-old girl with refractory nephrotic syndrome (NS) whose renal biopsy showed remaining immature embryonic-type glomeruli. She had been suffering from long-standing NS, which had onset at 2 years. Her initial renal biopsy at the age of 2 years showed minimal-change lesions and some embryonic-type glomeruli. These clinical observations suggested that early-onset NS might sometimes lead to mutation failure in embryonic -type glomeruli in selected patients. The patient was born at 38 weeks of gestation after an uneventful pregnancy and had a birth weight of 3272 g. The family history was unremarkable. The patient had been healthy until 2 years of age when massive proteinuria and generalized oedema developed. The diagnosis was NS, and treatment with prednisolone (PDN) at a dose of 20 mg/day (2 mg/kg) was initiated. Although the PDN treatment was initially effective for her proteinuria, a rapid recurrence of massive proteinuria occurred when the PDN dose was tapered. A percutanenous renal biopsy at the age of 2.4 years revealed minimal-change lesions and one (4%) glomerulus out of 28 glomeruli in the renal biopsy specimen showed the immature embryonic-type. Persistent hypoalbuminemia (less than 2.0 g/dL) lasting over 40 days required regular albumin infusions in order to preserve peripheral circulation. A 12-week course of cyclophosphamide (1.5 mg/kg), which was combined with PDN, resulted in a gradual decrease in urine protein excretion. For the next 6 years, frequent relapses occurred, and treatment with cyclosporine (CsA), 1.5 mg/kg, was started at the 5 th relapse at the age of 5.4 years. Although CsA was effective for the next 15 months, the 6 th relapse occurred soon after the PDN was discontinued. Because the relapse was due to a subsequently developed CsA-resistant state, tacrolimus (Tac), 0.075 mg/ kg, was initiated, 1