Kidney Histopathology and Prediction of Kidney Failure: A Retrospective Cohort Study.

RATIONALE & OBJECTIVE: The use of kidney histopathology for predicting kidney failure is not established. We hypothesized that the use of histopathologic features of kidney biopsy specimens would improve prediction of clinical outcomes made using demographic and clinical variables alone. STUDY DESIGN: Retrospective cohort study and development of a clinical prediction model. SETTING & PARTICIPANTS: All 2,720 individuals from the Biopsy Biobank Cohort of Indiana who underwent kidney biopsy between 2002 and 2015 and had at least 2 years of follow-up. NEW PREDICTORS & ESTABLISHED PREDICTORS: Demographic variables, comorbid conditions, baseline clinical characteristics, and histopathologic features. OUTCOMES: Time to kidney failure, defined as sustained estimated glomerular filtration rate ≤ 10mL/min/1.73m2. ANALYTICAL APPROACH: Multivariable Cox regression model with internal validation by bootstrapping. Models including clinical and demographic variables were fit with the addition of histopathologic features. To assess the impact of adding a histopathology variable, the amount of variance explained (r2) and the C index were calculated. The impact on prediction was assessed by calculating the net reclassification index for each histopathologic variable and for all combined. RESULTS: Median follow-up was 3.1 years. Within 5 years of biopsy, 411 (15.1%) patients developed kidney failure. Multivariable analyses including demographic and clinical variables revealed that severe glomerular obsolescence (adjusted HR, 2.03; 95% CI, 1.51-2.03), severe interstitial fibrosis and tubular atrophy (adjusted HR, 1.99; 95% CI, 1.52-2.59), and severe arteriolar hyalinosis (adjusted HR, 1.53; 95% CI, 1.14-2.05) were independently associated with the primary outcome. The addition of all histopathologic variables to the clinical model yielded a net reclassification index for kidney failure of 5.1% (P < 0.001) with a full model C statistic of 0.915. Analyses addressing the competing risk for death, optimism, or shrinkage did not significantly change the results. LIMITATIONS: Selection bias from the use of clinically indicated biopsies and exclusion of patients with less than 2 years of follow-up, as well as reliance on surrogate indicators of kidney failure onset. CONCLUSIONS: A model incorporating histopathologic features from kidney biopsy specimens improved prediction of kidney failure and may be valuable clinically. Future studies will be needed to understand whether even more detailed characterization of kidney tissue may further improve prognostication about the future trajectory of estimated glomerular filtration rate.

A Rare Case of Donor-Derived Renal Cell Carcinoma in a Kidney Transplant Recipient.

BACKGROUND The incidence of renal cell carcinoma (RCC) in transplanted kidneys is reported to be about 0.2%, which makes this case exceedingly rare. Risk factors include older age of the donors, smoking, obesity, and hypertension. Higher incidences of allograft RCC have been seen in patients who received a kidney from a deceased donor rather than from a living donor. CASE REPORT A 71-year-old woman with end-stage renal disease underwent deceased donor kidney transplantation (DDKT) 1 year before presentation. The immune-suppressive regimen was Envarsus, Myfortic, and prednisone. Allograft functioned with a baseline creatinine of 1.4-1.5 mg/dL. The patient presented due to recurring UTIs, which prompted the ultrasound that showed a mass on the allograft. Abdominal MRI demonstrated a 3.5-cm mass in the upper pole. Biopsy showed clear-cell RCC, Fuhrman nuclear grade 3. The patient underwent a partial nephrectomy. Following the nephrectomy, baseline serum creatinine was 1.7-2 mg/dL. The patient was discharged with immunosuppressive therapy consisting of Myfortic, prednisone, and Rapamune after diagnosis. CONCLUSIONS There are no standard treatment guidelines or optimal immune therapy for the management of allograft RCC in renal transplant recipients. Options include radical nephrectomy, nephron-sparing surgery (NSS), radiofrequency ablation (RFA), and active surveillance. According to a systematic review, the recurrence of cancer after partial nephrectomy was 3.6% after 3.1 years, which was similar to non-transplanted kidneys. There is not enough evidence to support screening for RCC in patients with transplanted kidneys, but constitutional symptoms like recurrent UTIs should prompt further investigation for potential malignancies in these patients.