Donors with renal cysts: a dilemma in decision making
Article Outline
In the Indian subcontinent where cadaveric transplantation is almost nonexistent, the majority of kidneys are obtained from living related donors Due to various reasons, the available related donors may not be acceptable. These two factors create a gap between demand and availability of donors. Ideally we should provide every recipient with a normal graft, but when this is not possible, we may be compelled to use a suboptimal graft. We, therefore, started accepting marginal donors including those from elderly persons, (older than 60 years), or more with structural abnormalities of the kidneys and pelvicalyceal system.1 Since 1997, we also have started using living related donors with renal cysts based on the encouraging outcomes of such kidneys in cadaveric transplant programs.2, 3, 4 This retrospective analysis of these patients assess, as the feasibility of accepting such kidneys and outlines an approach to dealing with a live related donor having renal cysts.
Materials and methods
Among 650 renal transplantation performed since January 1997, 27 donors had renal cysts that could be broadly classified into three categories: (1) a single cyst detected preoperatively (unilateral, 3; bilateral, 2); (2) multiple (up to 5) cysts detected preoperatively (unilateral, 11; bialteral, 6) or (3)cysts detected only at kidney exploration (five donors).
The cysts in all the donors met the criteria of simple renal cysts on computed tomography (CT) scan and ultrasound. When the differential glomerular filtration rate (GFR) was more than 25 mL/min (by DTPA scan), these donors were accepted for transplantation. Before proceeding to transplantation, we discussed in detail with the donor, recipient, and their family members the risks and benefits of accepting such kidneys. The donors were explored through a flank incision; recipient anaesthesia was withheld until the donor kidney was fully inspected for presence of other cysts. Once a final decision to accept the donor kidney was taken, the recipient surgery was started. During follow-up, graft function was evaluated by serial monitoring of serum creatinine and USG. Any cyst-related complications were noted.
Results
The mean age of the recipients was 36 years (range: 20 to 50 years). All donors with the preoperative diagnosis of single cyst (unilateral in three and bilateral in two) were accepted because no additional cyst was detected on exploration. At exploration, six donors with a preoperative diagnosis of multiple bilateral small renal cysts were found to have their kidneys studded with multiple cysts that were not detected on preoperative ultrasound or CT scan. Four of these donor nephrectomies were deferred and the transplantation was cancelled, as all of these donors were younger than 50 years of age. Two donors were accepted because they were older than 65 years of age. All donors with unilateral multiple cysts detected preoperatively were accepted because no additional cysts were detected on exploration. In five donors, multiple small cysts (2 to 3 mm in size) were seen on exploration and the kidney was not studded with cysts. The findings were discussed with the relatives of the patient; on their approval we proceeded with transplantation. All cysts were deroofed, the cavity was packed with surgicel, and the cyst margins were cauterized. At a mean follow-up of 21 months (range 2 to 37 months) all grafts are functioning well, and there have been no cyst-related complications in any recipient.
Discussion
Simple renal cysts are a common finding in the normal population older than 50 years of age where their incidence is 25% to 40%. The entity of multiple renal cysts is well described and is different from autosomal dominant polycystic kidney disease (ADPKD).
There are many reports on the use of cadaveric kidneys with cysts. On long term follow-up, they are found to provide adequate renal function until there is graft failure due to the growth of the cysts or from some other reasons. Living donors with renal cysts constitute a complex group. When such donors are encountered the important questions to be answered are as follows: (1) Are we dealing with a potential ADPKD candidate? and (2) What is the donor safety if the donor later develops cysts in the other kidney? All workers agree that a single cyst detected preoperatively or even when detected on exploration can be incised, the kidney can be safely used for engraftment. A landmark study5 regarding the natural progression of ADPKD and its outcome in terms of end-stage renal disease revealed that the average time span (12.5 years) was similar for uninephrectomized individuals as compared with those who retained both kidneys. If the donor has a simple renal cyst and does not harbour ADPKD, then cyst growth is relatively slow, especially if the donor age is older than 50 years of age.6 Therefore, we feel that by accepting donors older than 60 years of age, we are not compromising the lives of the donors if they have bilateral simple cysts as these cysts will grow slowly in elderly donors. More so, even if such a donor has ADPKD, it will not matter whether the donor has a single kidney or both kidneys. The younger ages (younger than 50 years) of 4 donors was the basis of not accepting them when their kidneys were found to be studded with cysts because in the age group younger than 50 years, cysts have been shown to grow faster. ADPKD is polygenic with varible penetrance, so, even if we detect it by genetic study, it will be difficult to predict the outcome and degree of manifestation.
There are obvious advantages of transplantation over dialysis even if we are using kidneys with cysts. The earlier reports of the use of cadaveric kidneys and live related donor kidneys with cysts7, 8, 9 have clearly shown that the growth of these cysts is slow. In 1 case, it took 10 years for the cysts to develop sufficiently to cause loss of graft function and pain requiring graft nephrectomy.10 The long-term graft and patient survival data for recipients having a graft with a cyst are not available at present. Once they are available, we will be able to further assess the feasibility of using such kidneys for transplantation.
We feel that whenever there is a donor with multiple cysts detected preoperatively, we should perform a laparoscopic exploration of the donor kidney to assess the presence of other cysts. This will reduce morbidity of the donor if the donor is not accepted later on due to the presence of numerous cysts. We have started doing laparoscopic live donor nephrectomy for the last 2 years and have found this approach more acceptable.
The detection of the presence of cysts only at exploration in five donors and the presence of additional cysts in other donors underline the limitations of currently available imaging modalities for the preoperative diagnosis of small cysts. We, therefore, delay induction of recipient anesthesia as a policy until the donor kidney has been inspected.
The likelihood of dealing with a cystic tumour also needs to be addressed. It is well known that cysts that meet all criteria of Bosniak type 1 cysts have low potential for malignancy. Because our donor cysts met all criteria of Bosniak type I cysts and on exploration none had an irregular wall or turbid/hemorrhagic content, we did not perform a frozen section biopsy of the cyst wall or a biochemical evaluation of the fluid, but certainly advocate this should there be any doubt.
In 2 potential donors where the cysts appeared complex (Bosniak type 3 to 4), we performed frozen section biopsies and on detection of malignancy, the kidney was removed and the transplantation, cancelled. Such complex cysts can be recognized easily and all attempts should be made to rule out malignancy.
Conclusion
In the event of preoperative diagnosis of the presence of cysts, the donor should undergo exploration, and recipient anesthesia withheld until, one makes the decision to use kidney. Laparoscopic visualization may reduce the morbidity of exploration in the future. Our observation makes us support the use of kidneys with a cyst if the donor is elderly and there are only a few small cysts (< 5 mm in diameter). The decision to use such kidneys should be made in consultation with both donor and recipient, depending on the availability of other donors.
References
PII: S0041-1345(02)03876-9
doi:10.1016/S0041-1345(02)03876-9
© 2003 Elsevier Science Inc. All rights reserved.
