Small renal masses in kidney transplantation:Overview of clinical impact and management in donors and recipients

Kidney transplantation is the best replacement treatment for the end-stage renal disease.Currently,the imbalance between the number of patients on a transplant list and the number of organs available constitutes the crucial limitation of this approach.To expand the pool of organs amenable for transplantation,kidneys coming from older patients have been employed;however,the combination of these organs in conjunction with the chronic use of immunosuppressive therapy increases the risk of incidence of graft small renal tumors.This narrative review aims to provide the state of the art on the clinical impact and management of incidentally diagnosed small renal tumors in either donors or recipients.According to the most updated evidence,the use of grafts with a small renal mass,after bench table tumor excision,may be considered a safe option for high-risk patients in hemodialysis.On the other hand,an early small renal mass finding on periodic ultrasound-evaluation in the graft should allow to perform a conservative treatment in order to preserve renal function.Finally,in case of a renal tumor in native kidney,a radical nephrectomy is usually recommended.

Natural History of Small Renal Masses

Objective：To review the natural history and growth kinetics of small renal masses （SRMs）.Data Sources：The literature concerning natural history and growth kinetics of SRMs was collected from PubMed published from 1990 to 2014.Study Selection：We included all the relevant articles on the active surveillance （AS） or delayed treatment for SRMs in English,with no limitation of study design.Results：SRMs under AS have a slow growth potential in general.The mean linear growth rate is 0.33 cm/year,the mean volumetric growth rate is 9.48 cm3/year.The rate of metastasis during AS is below 2％.Some factors are associated with the growth rate of SRMs,including tumor grade,histological subtype,initial tumor size,age,radiographic characteristics,and molecular markers.No definite predictor of growth rate of SRMs is defined at present.SRMs with high tumor grade and the subtype of clear cell renal cell carcinoma may have aggressive growth potential.Conclusions：AS is a reasonable choice for elderly patients with SRMs,who are at high risk from surgery.Progression during observation is the biggest concern while performing AS.There is no definite predictor of progression for SRMs under AS.Percutaneous renal biopsy providing immunohistological and genic biomarkers may improve the understanding of natural history of SRMs.