Clinicopathologic Impact of Early Medullary Ray Injury in Patients Following Kidney Transplantation

Transplant Proc. 2017 Jan-Feb;49(1):78-83. doi: 10.1016/j.transproceed.2016.10.021.

Abstract

Background: Previously, we explored the histopathologic characteristics of medullary ray injury (MRI) inducing interstitial fibrosis and tubular atrophy (IF/TA) to determine its etiologies, which include calcineurin inhibitor (CNI) toxicity and urologic complications. However, we did not examine the effects of these etiologies on long-term kidney allograft prognosis, because biopsy timing differed among cases.

Aim: We examined the influence of early MRI on kidney allograft prognosis using protocol biopsies taken within a 3-month time frame.

Methods: We defined early MRI as tubular degeneration with interstitial edema or mild fibrosis localized to the medullary ray. We divided 53 protocol biopsies into 2 groups, with and without early MRI. Early MRI+ cases with isometric vacuolization were classified as CNI toxicity; those with Tamm-Horsfall protein in the interstitium and a thyroidlike appearance were classified as urinary tract system abnormalities; remaining cases were classified as "others." We compared changes in serum levels of creatinine (sCr) over 3 years and fibrosis extent at 1 year.

Results: The sCr levels were significantly higher in the MRI+ group than the MRI- group at 3 years (P = .024). Examining the 3 MRI+ subgroups, only the MRI+ urinary tract system abnormalities group had significantly high sCr levels compared to the MRI- group (P = .019). The MRI+ group showed significant signs of IF/TA at 1 year.

Conclusions: Early MRI after kidney transplantation was significantly more likely to develop IF/TA at 1 year and had higher sCr levels at 3 years. In such cases, intervention might preserve graft function over the long term.

MeSH terms

  • Adult
  • Biopsy
  • Creatinine / blood
  • Female
  • Fibrosis / pathology
  • Graft Rejection / pathology*
  • Humans
  • Kidney / pathology*
  • Kidney Transplantation / adverse effects*
  • Male
  • Middle Aged

Substances

  • Creatinine