2021 Volume 69 Issue 4 Pages 209-215
We describe a rare case of cyst formation in RCC metastasis to the liver, which showed extremely slow progression over 9 years.
A 60-year-old man under maintenance hemodialysis for renal failure due to polycystic kidney disease received a left nephrectomy for Stage I RCC 9 years earlier. Analysis of the tissue was histologically confirmed as clear cell RCC along with partial sarcomatous change. He was also noted as having a cyst formation tumor of 15mm in diameter at S6 in the liver, which was depicted as a non-contrasted lesion in the early phase and an iso-echoic lesion in the Kupffer phase by contrast-enhanced ultrasonography using Sonazoid, indicating that the lesion was not malignant. The hepatic cystic lesion had increased to a size of 60mm in diameter 5 years later, but exhibited no solid formation and resembled a hemorrhagic liver cyst. However, the lesion became gradually enlarged, with accompanying cystic lesions that were depicted as high-intensity MRI T2 images surrounded by a high-intensity area in MRI diffusion images along with a solid lesion showing reduced uptake of SPIO. Those findings suggested an angiosarcoma or liver metastasis of RCC. A tissue specimen of the tumor obtained after a right hepatic lobectomy displayed malignant cells on the wall of the cystic lesion, which was compatible with metastasis of clear cell RCC. Moreover, it was apparent that although the hepatic cystic tumor lesion was affected by hemorrhage, it was increased in size by the retention of serous components. Thus, a cystic, and not sarcomatous, component appeared to slowly enlarge the lesion. No additional metastasis was detected by PETCT after surgical treatment. Clinicians should consider hepatic metastasis of RCC when encountering a tumor in the liver, even a cystic lesion, in patients with a history of RCC.
