De novo focal segmental glomerulosclerosis and kidney hypertrophy associated with progressive obesity after kidney transplantation

Background: Obesity is an important problem associated with worsening cardiovascular disease and the progression of proteinuria in kidney transplant recipients. We describe a case of de novo focal segmental glomerulosclerosis (FSGS) associated with progressive obesity after kidney transplantation (KTx). Case Presentation: A 41-year-old male patient underwent an allograft kidney biopsy because of nephrotic range proteinuria. The donor was his father who was aged 70 years at transplantation. In addition, there was a substantial difference in body weight (BW) between the recipient and donor. At 56 months after kidney transplantation, the patient’s BW increased from 83.1 kg (BMI, 29.3 kg/m2 ) before kidney transplantation to 93.9 kg (BMI, 33.1 kg/m2 ). An allograft biopsy showed glomerular hypertrophy and focal segmental sclerotic lesions with partial epithelial cell hyperplasia. The histologic diagnosis was FSGS, not otherwise specified (NOS) variant. A comparison between the kidney volume before and after kidney transplantation, evaluated using volumetric computed tomography, revealed prominent kidney hypertrophy (1.77 times). Conclusions: Our case demonstrated that de novo FSGS after kidney transplantation is induced by progressive obesity, as manifested by glomerular hypertrophy as well as kidney hypertrophy. This is a hyperdynamic state contributed to the pathogenesis of de novo FSGS. Our report is important to understand the pathogenesis of FSGS.