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

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).
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).
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.