Detection and follow-up of a renal cell carcinoma in a transplant kidney by CEUS

Purpose: CEUS is an important method for the diagnosis of RCC (renal cell carcinoma) in native kidneys. Tumors in transplant kidneys rarely occur due to the reduced life expectancy (both of patient and transplant). We describe the change in perfusion characteristics, monitored by CEUS, over a period of two and a half years.

Material and methods: An 81-year old asymptomatic patient had undergone renal transplantation 22 years ago. A nodule in the transplant kidney with a diameter of 17 mm was first diagnosed 6/2010. A follow-up in 1/12 showed progression in size (33 × 22 mm) and a change in CEUS characterization. The lesion then was very suspicious of a malignant tumor. As the patient did not wish an operation, another follow-up was performed in 12/12 with the same CEUS pattern. Finally the patient gave consent to partial resection. Histology yielded an RCC.

Fig. 1: Tumor wash out at follow up

Results: In the first CEUS there was no differentiation of the nodule from the surrounding normal tissue, neither in the early nor in the late phase. At follow-up 18 and 29 months later part of the lesion showed early hypoenhancement and wash out in the late phase.

Conclusion: RCC can show insuspicious CEUS characteristics especially when small and may change its perfusion pattern over time. This rare case-report of a tumor in a transplant kidney suggests, that regular follow-up of renal nodules, even when not suspicious in initial CEUS, is mandatory.