De novo renal cell carcinoma in a kidney allograft with focus on contrast-enhanced ultrasound.

The development of de novo renal cell carcinoma (RCC) in a transplanted kidney is a rare condition. Currently, this is the second case report of a 41-year-old man in whom carcinoma of a renal allograft was detected by contrast-enhanced ultrasound (CEUS). An abdominal CT scan was not conclusive enough to differentiate between septal enhancement of a cyst and a low vascularized tumor. CEUS confirmed a solid, homogeneously enhancing but hypoechoic and hypovascular lesion compared to the surrounding kidney parenchyma without septal enhancement. Therefore, the patient underwent nephron-sparing surgery (NSS), affirming papillary RCC type 2. Graft function remained unchanged postoperatively; 12 months after NSS, no local recurrence or distant metastasis was described. CEUS seems to be a minimally invasive and efficient imaging option if other diagnostic tools cannot clearly exclude RCC, with the advantage of wide-ranging use, especially in cases of impaired renal function. 2014 S. Karger AG, Basel.