Objective  To investigate the clinicopathological features of recurrent and de novo focal segmental glomerulosclerosis (FSGS) after kidney transplantation.

  Methods  Thirty-four recipients pathologically diagnosed with FSGS by renal allograft biopsy were enrolled in this clinical trial. According to the detection of primary diseases of renal allografts and circulating permeability factors, 34 recipients were divided into the recurrent FSGS group (n=12) and de novo FSGS group (n=22). The differences of clinical indexes and the degree of pathological injury of renal allografts were compared between two groups.

  Results  There was no significant difference in the mesangial hyperplasia score, glomerulosclerosis rate, renal tubular atrophy score, interstitial fibrosis score and podocyte proliferation rate between two groups (all P > 0.05). In the recurrent FSGS group, segmental glomerulosclerosis rate of the recipients was 0.10 (0.08, 0.27), lower than 0.19 (0.13, 0.33) in the de novo FSGS group (P < 0.05). No significant difference was found in the incidence of antibody-mediated rejection, drug-induced renal tubular injury and BK virus infection between two groups (all P > 0.05). The incidence of T cell-mediated rejection in the recurrent FSGS group was 17%, lower than 55% in the de novo FSGS group (P < 0.05). Immunohistochemical staining showed that the infiltrating inflammatory cells in the renal allografts were mainly T lymphocytes. The positive rates of C4d deposition in peripheral capillaries between the recurrent and de novo FSGS groups were 33% (4/12) and 32% (7/22), with no significant difference (P > 0.05). Immunofluorescence results revealed IgM deposition in the segmental glomerulosclerosis area of renal allografts in most cases. Electron microscopy showed extensive fusion or segmental distribution of podocytes in the glomerulus of renal allografts.

  Conclusions  The degree of renal functional injury and the incidence of T cell-mediated rejection in the recurrent FSGS group are lower than those in the de novo FSGS group. Comprehensive analysis of preoperative and postoperative clinical manifestations, laboratory testing and pathological examination of kidney transplant recipients contribute to early diagnosis and treatment of recurrent and de novo FSGS.