A blue kidney in a living donor

A case report on lipofuscin deposition in a graft biopsy two years after kidney transplantation: an insignificant bystander or a pathogenic benefactor?

Background

Lipofuscin deposition is a characteristic manifestation of aging. There is very limited literature in humans and in animals describing these deposits in native kidneys. Overall, it is thought to be non-pathogenic and successful transplants from a donor with lipofuscin deposits have been reported. We present the case of a patient who underwent a kidney transplant and a for-cause biopsy post-transplantation incidentally revealed lipofuscin deposition.

Case presentation

A 48-year old gentleman with a past medical history of diabetes, hypertension, coronary artery disease, and ischemic and then hemorrhagic cardiovascular accident underwent a successful kidney transplant. His donor was an expanded criteria donor with no major past medical history. Post-transplant course was complicated by delayed graft function requiring one dialysis treatment for hyperkalemia. After that he had an uneventful course and achieved a baseline creatinine of 1.2 mg/dL, with no proteinuria. On a routine 19-month follow-up he was noted to have proteinuria and an antibody against the major-histocompatibility-complex class I-related chain A. A graft biopsy revealed acute antibody-mediated rejection and impressive lipofuscin deposition. He was subsequently treated with an antibody-mediated rejection protocol that included high dose steroids, Rituximab, plasmapheresis, and intravenous immunoglobulin, but responded poorly to this regimen. A 6-month follow up biopsy continued to show lipofuscin deposition, with similar microvascular injury scores and 12-months later his creatinine remained stable but his proteinuria worsened. Patient was struggling with recurrent infectious episodes requiring hospitalizations and thus no further diagnostic or therapeutic treatments were pursued.

Conclusions

Lipofuscin deposition has been reported in solid organ transplants but the significance and cause are not well understood. Several physiologic and some pathologic causes to these deposits have been reported including age, diabetes, medications and a genetic syndrome. We propose that immunologic causes such as rejection in the presence of other risk factors could potentiate the oxidative stress leading to excessive lipofuscin deposition in kidney transplants. In the case of our patient, we conclude that these deposits were likely recipient-derived, and postulate that the cumulative burden of inflammation from rejection, and underlying medical conditions led to increased lipofuscin deposition. We speculate them to be an innocent bystander.

Transplantation of a Blue Kidney: A Case Report

A blue kidney, although very rare, can be encountered upon a live kidney donor. Literature has shown hemosiderin deposits, lipofuscin pigment, and melanosis as possible reasons. We report on a 37-year-old woman who wished to donate a kidney to her husband. The donor's preoperative biochemistry and imaging tests showed normal renal function. During the laparoscopic left kidney nephrectomy, the kidney was observed to be blue in color. Perioperatively, Doppler ultrasonography was used to rule out vascular reasons, and a wedge biopsy was performed. The other kidney was also explored, and it turned out to be blue as well. Histopathological analysis showed melanosis in the tubules without malignity or pathologic changes in the glomeruli, the interstitium, or the vessels. Even though some causes of blue kidney may result in impairment of the renal function, after the necessary tests show no signs of malignity and functional impairment, a blue-colored kidney may be suitable for transplantation.

Normal black kidney

A black kidney has 3 major differential diagnoses: hemosiderosis, lipofuscin pigment and melanotic renal cell carcinoma. Excluding lipofuscin, the other 2 are accompanied by an abnormal renal function. We report on a 25-year-old man who intended to donate a kidney to his cousin. On the operating room table when we incised the left flank region and exposed the kidney, we found a firm and black kidney so the operation was cancelled due to potential vascular injuries. Days after the incomplete procedure, we reviewed the donor's biochemistry and imaging to reassess his renal function, but the results showed quite normal renal function again. The result of Ham test was also negative. Two weeks later, we began the operation, removed the same left kidney and found that it was in the same conditions as it was before. We took the opportunity to send needle biopsies of the kidney for histopathologic analysis. The analysis showed a melanotic kidney without pathological changes in glomeruli and interstitium and vessels. A black kidney may result in hemosiderin, lipofuscin or melanin deposits in the kidney, which can confirm the diagnosis; however, special tests for underlying disease and renal function should be considered. Some causes of black kidney lead to abnormal function, but our patients's kidney returned to normal.