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Angiomyolipoma is the most common benign neoplasm of the kidney. Successful transplantation of an AML affected kidney has been reported. However it is still often seen as a contraindication to transplantation.
A 47-year-old female underwent assessment for a direct specified kidney donation to her husband who had end stage renal failure, due to adult polycystic kidney disease. Routine pre-operative CT angiography demonstrated a large 6 cm × 4 cm AML arising from the upper pole of the right kidney. Right-side hand assisted retro-peritoneoscopic live donor nephrectomy with bench tumour excision was subsequently performed. Recipient implantation was unremarkable with no haemorrhage.
Histology confirmed a 7 cm AML. At 36 months follow up, the recipient's serum creatinine was 158 μmol/l and eGFR 40 ml/min without the need for dialysis at any stage.
AML should not be a contraindication for specified live kidney donation, despite a size of 7 cm.
Angiomyolipoma (AML) is the most common benign neoplasm of the kidney.1 It is a tumour composed of variable amounts of mature adipose tissue, smooth muscle, and vessels derived from perivascular epitheloid cells. Its prevalence in the general population has been reported to be between 0.1 and 0.22%.2 AML appears in two distinct settings; either associated with tuberous sclerosis or sporadic in nature. The clinical presentation of AML is variable. Often patients are asymptomatic, however, they can present with the classic triad of flank pain, a tender mass and gross haematuria. They are commonly identified incidentally during radiological investigations. These tumours have the potential for life-threatening haemorrhagic rupture. In this setting patients can present with sudden acute abdominal pain and haemorrhagic shock. After renal cell carcinoma, AML is the second most common renal cause of retroperitoneal hemorrhage.3
AML's can be diagnosed by ultrasound and computerised tomography (CT) imaging. It is important to differentiate an AML from renal carcinoma. AML has a characteristic sonographic appearance of hyper echoic signal and acoustic shadowing.4 The CT diagnosis is confirmed by the appearance of fat within the renal lesion.
As a benign lesion that is frequently asymptomatic, AML usually does not require any intervention. Indications for intervention include suspicion of malignancy, haematuria, renal failure and rupture. It has been demonstrated that tumour size (>4 cm) identified on CT, is the most reliable predictor of rupture.1,5,6
Angiographic embolisation is the treatment modality of choice. It has the advantage of preserving renal parenchyma and avoids the risks associated with potentially major surgery.4 Failure of radiological management in the acute setting may necessitate total or partial nephrectomy.
We present a case of a large AML excised from a living donor kidney, leading to successful transplantation and outcome for both donor and recipient.
A 54-year old pre-emptive transplant patient, suffering from adult polycystic kidney disease was deemed suitable for transplantation with his wife as a donor. His co-morbidities include obesity with a BMI of 30 (height 177 cm, weight 93 kg), porphyria carrier (with two previous deep vein thromboses) and treated hypertension. His pre-operative urea was 21.9 mmol/l, creatinine 349 μmol/l and estimated glomerular filtration rate (eGFR) 14 ml/min.
His 47-year-old wife underwent assessment for living donation with no contraindications. She had no significant co-morbidities, a BMI of 23 (height 152 cm, weight 52.5 kg), serum creatinine of 85 μmol/l and eGFR of more than 60 ml/min. Pre-operative CT angiography demonstrated a large 6 cm × 4 cm AML arising from the upper pole of the right kidney.
In addition to the routine consent procedure for a live donor renal transplantation, the donor was also consented for rupture of the AML, recurrence, possible graft damage and/or no transplantation.
The donor underwent a right-side hand assisted retroperitoneoscopic live donor nephrectomy with ex vivo tumour excision (Figs. 1 and 2). The operative procedure was unremarkable. The macroscopically tumour free resection margin was reviewed and retrograde insufflation of methylene blue was used to identify calyx lesions. Two lesions were closed using PDS 5/0, followed by closure of the resection surface using BioGlue (CryoLife Inc., USA) to achieve haemostasis.
The recipient's implantation involved a routine kidney transplant approach to the external iliac vessels; reperfusion was homogenic with no bleeding from the resection site.
The patient had prompt kidney graft function with a slow decline of creatinine. He was discharged from hospital on day 4 post transplantation. His transplant ureteric stent was removed 6 weeks after transplantation and he continued on maintenance immunosuppression with prednisolone 5 mg daily and tacrolimus 2 mg twice a day.
At 36 months follow up, the donors creatinine and eGFR are 104 μmol/l and 49 ml/min respectively. While the recipient's serum creatinine is 159 μmol/l and eGFR 40 ml/min. In our department, a routine 3-month biopsy is performed to diagnose early graft rejection. However, the patient is anticoagulated with warfarin due to his previous history of multiple DVT's. The routine post transplant biopsy would therefore, only be indicated if the recipient's renal function significantly declined. This elevated creatinine represents the donor/recipient weight mismatch.
Histology confirmed a 7 cm benign AML tumour, which was larger than the CT angiographic findings.
We present a large AML tumour excised from a direct specified living donor kidney, prior to transplantation. The first case of a direct specified live donor kidney transplantation after ex vivo excision of AML was performed in 1993.7 There have been several reports of successful renal transplantation with AML in situ. In one case, the lesion was left in situ due to its small size and central location.8 Follow up radiological studies of the lesion have shown no further increase in size despite immunosuppression 18 months post operatively. There have been reports of ex vivo excision of AML in cadaveric kidneys.9 Others have opted for an in vivo excision of an AML under cold ischaemia prior to nephrectomy and transplantation.10 Proposed benefits of in vivo excision include, the ability to extensively evaluate the repair to the excision site at the theoretical expense of an additional re-perfusion episode after cold ischaemia. However we believe the ex vivo approach was more favourable owing to the AML size and location as it provided a more controlled environment, i.e. no risk of bleeding during the dissection. Cold ischaemia time is short in the live donor setting, therefore not significantly longer following the ex vivo dissection. Radiological angiographic embolisation would have been an option, however, after discussion with our radiology colleagues, it was felt that the location and size made for a high risk of failure and recurrence through this approach. Taking this into account we proceeded with a meticulous back table resection. Only the tumour was excised, sparing all the renal parenchyma and avoiding the complications associated with embolisation.
AML has two recognised aetiologies; associated with the tuberous sclerosis complex of pathologies or sporadic in nature. The donor's DNA was not examined for the presence of tuberous sclerosis due to the nature of her AML. In tuberous sclerosis, tumours are often larger and affect multiple organs. There was no evidence of this on her pre-operative investigations. Furthermore in tuberous sclerosis, AML's are often bilateral and diagnosed in childhood or early adult life.
The AML affected kidney was utilised, which reduced the risk of life threatening haemorrhage associated with large AMLs. The donor was particularly happy to be helping her loved one whilst also being treated simultaneously in one procedure.
Despite the high risk of rupture and intra-operative bleeding, with careful pre-operative planning and meticulous intra-operative care the removal of the AML and direct specified kidney transplantation was possible.
Advances in surgical management have helped to expand the pool of potential organ donors. Kidneys previously considered marginal or unsuitable due to benign lesions are now given consideration.
As illustrated, large AML's should not be an absolute contraindication for direct specified kidney transplantation. There is no evidence in the literature to demonstrate recurrence post direct specified kidney transplantation; however patients must be consented for this possible complication. With careful assessment within a multidisciplinary team, including nephrologists, transplant surgeons, urologists, radiologists and histopathologists, patients’ quality of life and prognosis can be significantly improved.
The authors of this manuscript have no conflict of interest to disclose as described by International Journal of Surgical Case Reports. The Results presented in this paper have not been published previously in whole or part.
Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.
Mr. Nicos Kessaris has done the study conception and design. He along with Mr. Hamid Abboudi and Mr. Pankaj Chandak drafted the article. Though, Mr. Jiri Fronek teamed with the latter two to carry out study conception and design works, he played an instrumental role in the final approval of the version to be published.