Renal Transplantation: Immediate and Late Complications

Kidney grafts are the most common transplanted solid organ. To optimize graft survival, radiologists should be familiar with the anatomy and potential complications unique to transplanted kidneys. In addition to being able to recognize the imaging characteristics to diagnose etiologies of kidney graft dysfunction, an understanding of the pathophysiology is a key to narrowing the differential diagnosis. This article provides a summary of the most common complications based on broad categories of type of complication and posttransplant timing.

Functional MRI to quantify perfusion changes of a renal allograft after embolization of an arteriovenous fistula

Acute allograft injury was observed in a 37-year-old woman within a few weeks after kidney transplantation. Neither renal ultrasound nor computerized tomography (CT) and magnetic resonance (MR) angiography revealed any anomaly. An MR protocol was then performed including arterial spin labeling and intravoxel incoherent motion diffusion weighted imaging. Both arterial spin labeling and the perfusion fraction in the diffusion weighted imaging showed decreased perfusion compared to reference values. The patient subsequently underwent angiography, where an arteriovenous fistula in the upper calix of the transplant kidney was detected and immediate embolization was performed. A second functional MR, performed one week later, demonstrated a 40% increase in organ perfusion. We conclude that functional MR with arterial spin labeling and intravoxel incoherent motion have the potential to provide complementary information of clinical value to conventional imaging for monitoring renal allografts.

Urothelial carcinoma of the graft kidney with molecular analyses: a rare case report

Background

Malignancy after transplantation is a leading cause of death among kidney transplant recipients. However, donor-derived malignancies are rare. We report a case of a high grade papillary urothelial carcinoma arising in a transplanted kidney.

Case presentation

A 62-year-old female who received a kidney transplantation more than 30 years ago presented with urinary tract infection, acute renal failure, and hydronephrosis of the transplant kidney. Anterograde nephrostogram showed a large filling defect in the lower pole of the transplant kidney and in the proximal 3–4 cm of the ureter. A biopsy from the renal pelvic mass showed a high grade urothelial carcinoma. She underwent an anterior exenteration, resection of both transplant and native kidneys and bilateral pelvic lymph node dissection. Pathologic examination showed a high grade papillary urothelial carcinoma which appeared to arise in the pelvis of the graft kidney, involve the graft ureter and native urinary bladder. The tumor had metastasized to one left obturator lymph node but spared the two native kidneys and ureters. Short tandem repeat (STR) analysis confirmed the tumor to be of donor origin. Next-generation sequencing identified amplification of TERT and loss of CDKN2A/CDKN2B in the primary tumor.

Conclusion

While it is known that transplant recipients have an increased risk of urothelial carcinoma compared to the general population, the lack of the well-documented risk factors, such as older age at transplantation, BK polyomavirus infection, and prolonged post-transplantation history and dissemination of the tumor in this case shed light on the de novo tumorigenesis of the graft kidney within the host microenvironment. Amplification of Telomerase reverse transcriptase (TERT) and loss of cyclin dependent kinase inhibitor 2A/2B (CDKN2A/CDKN2B) detected in the tumor by next gene sequencing suggests that they may play an important role in this case.

Successful Endovascular Control of Renal Artery in a Transplant Kidney During Nephron Sparing Surgery (NSS) for Large Centrally Located Tumor

Renal cell carcinoma in a transplant kidney is a rare condition. Nephron Sparing Surgery (NSS) is the treatment of choice. One of the main technical challenges is obtaining adequate vascular control. We present a rare case of large centrally located hillar tumor in a kidney 18 years after transplantation treated with NSS. Vascular control was achieved by using a novel approach. Post-operative course was uneventful with minimal decrease in renal function. We believe that this unique choice of treatment can be used in cases of NSS where the access to the renal pedicle is limited.

Assessment of postoperative perfusion with contrast-enhanced ultrasonography in kidney transplantation

The aim of this study was to use contrast-enhanced ultrasound (CEUS) to evaluate renal perfusion after kidney transplantation and investigate the clinical significance of CEUS in monitoring postoperative renal perfusion. Thirty-five patients who underwent kidney transplantations were included in this study and divided into two groups-normal and abnormal-based on their serum creatinine (SCr) levels. Conventional ultrasound and CEUS were used to monitor renal perfusion after kidney transplantation. The differences in the results between the two groups were then compared. Color doppler ultrasonography showed that there were significant differences in the resistance index (RI) and the pulsatility index (PI) of the interlobar artery between the groups. Furthermore, CEUS indicated a significant difference between the two groups regarding the slope rate of the cortical ascending curve (A1), the medullary ascending curve (A2), and the derived peak intensity (DPI1). CEUS precisely showed the characteristics of microcirculation in renal parenchyma after kidney transplantation. It also detected changes in the microcirculation, which was a new method of evaluating tissue perfusion in transplanted kidneys.

Femoral herniation of transplanted ureter after deceased-donor kidney transplantation

INTRODUCTION

Herniation of the ureter after kidney transplant is a rare and under documented event. Many of these herniations are due to abdominal wall defects or ureteral redundancy. After an extensive review of available literature, there has not been a reported case of a femoral herniation of ureter after kidney transplant. We report a case of late allograft renal transplant failure due to ureteral obstruction secondary to femoral herniation of the ureter.

CASE PRESENTATION

We report a case of 64 year old male with a history of kidney transplant, who was found to have an inguinal bulge. He was diagnosed with a femoral hernia containing transplant ureter using transplant kidney ultrasound and CT of the abdomen and pelvis. Subsequently he developed transplant kidney failure due to obstructive uropathy from the femoral hernia. The patient underwent a femoral hernia repair with biologic mesh. Compromised ureter was excised and a neoureterocystostomy was created. Post operatively his creatinine returned to baseline.

DISCUSSION

In our literature search there are two types of inguinal ureteral hernias described. Paraperitoneal, which makes up the majority of the cases, and extraperitoneal. There are no classifications for ureteral femoral hernias. We may extract these definitions to femoral hernias, as evidenced by our case where we encountered a paraperitoneal femoral hernia containing transplant kidney ureter.

CONCLUSION

To the best of our knowledge this is the first reported case of a femoral ureter hernia. Due to its rarity in the literature, an understanding of management is critical to patient outcome.

The first use of Resonance(®) metallic ureteric stent in a case of obstructed transplant kidney

INTRODUCTION

To date, double JJ stent is the mainstay ureteric stent used in a transplant kidney. We herein report the first use of Resonance(®) metallic ureteric stent to manage ureteric obstruction in a transplant kidney.

PRESENTATION OF CASE

A 45-year-old lady underwent an uneventful living related donor renal transplantation. Due to post-operative pelvi-ureteric obstruction and recurrent obstruction following multiple distal stent migration and expulsion necessitated frequent nephrostomy insertion and antegrade stenting, she underwent challenging but successful retrograde insertion of a 12 centimetres long and size 6.0 French Cook Resonance(®) metallic ureteric stent which was performed under general anaesthesia.

DISCUSSION

Metallic ureteric stents are a fairly recent introduction to modern urology and they have been successfully used in the management of benign and malignant obstruction of ureter.

CONCLUSION

This is the first case of therapeutic metallic ureteric stent insertion in a transplant kidney.