Clinical Significance Of Adherent Perinephric Fat In Partial Nephrectomy

Objective : To establish the grading standard of PFAD(perinephric fat adhesion degree),analyze the clinical risk factors,imaging predictors and pathological features of PFAD based on fixed standard classification,and evaluate the effect of APF(adherent perinephric fat)on the perioperative outcome of RLPN(retroperitoneal laparoscopic partial nephrectomy).Methods: The clinical data,imaging data and perioperative data of 84 patients who underwent continuous RLPN surgery in our hospital were collected.According to the characteristics of perinephric fat separation during partial nephrectomy,the classification standard of perinephric fat was established by watching the complete operation video repeatedly after follow-up operation and after operation.According to the complexity of renal fat separation during operation,the patients were divided into NPF(normal perinephric fat)group,Mi PF(mild adherent perinephric fat)group,Mo PF(moderate adherent perinephric fat)group and SPF(severe adherent perinephric fat)group.The clinical data and imaging data were extracted,and the clinical risk factors and imaging predictors related to PFAD were found by univariate and multivariate sequential logistic regression analysis.The perioperative data were compared between the APF group and the non-APF group,which affected the surgical complexity.After operation,the perinephric fat of patients was stained with Masson,CD34 and CD45 respectively.The distribution of collagen,blood vessels and immune cells in perinephric fat of APF and non-APF group was observed and analyzed under microscope.Results:1.Of the 84 patients enrolled,20(23.8%)were in the NPF group,28(33.3%)in the Mi PF group,18(21.4%)in the Mo PF group and 18(21.4%)in the SPF group.The proportion of patients with renal cell carcinoma and hypertension,perinephric fat area and perinephric fat thickness increased with the increase of PFAD.The proportion of patients with no,mild to moderate and severe Strandingwas 61.9%,28.6% and 9.5%,respectively.2.Univariate and multivariate analysis showed that male,advanced age(> 55yr)andhypertension were significantly positively correlated with PFAD among the clinical risk factors of APF.There were only 2 patients with chronic kidney disease,which could not be statistically analyzed,but they were all in SPF group.In the univariate analysis of imaging predictors of APF,perinephric fat thickness(medial perinephric fat thickness,lateral perinephric fat thickness,posterior perinephric fat thickness and posterolateralperinephric fat thickness),perinephric fat area,perinephric fat density and Stranding were significantly correlated with PFAD.The posterior perinephric fat thickness,perinephric fat density and Stranding selected by multivariate analysis can be used as imaging predictors of PFAD.3.Comparing the perioperative outcomes and postoperative pathology between the APF group and the non-APF group,it was found that APF only caused a significant increase in postoperative drainage(P < 0.05).4.Immunological and histological analysis showed that a large number of immune cells gathered into mass in the renal cortex near the renal capsule of APF,and there were also a lot of immune cells infiltration in the renal capsule.In addition,the renal capsule thickened and neovascularization increased in APF group.Conclusions:Elderly male patients with hypertension are more likely to suffer from APF,.According to the posterior perinephric fat thickness,perinephric fat density and Stranding imaging predictors,the evaluation of PFAD,before RLPN is helpful to guide the preoperative choice of operation.The pathological features of APF reflect the characteristics of subcapsular exfoliation and hemorrhage in patients with APF during renal mobilization of RLPN.