Metastatic renal cell carcinoma within a hepatic focal nodular hyperplasia: a case report and review of the literature.

A patient with microscopic metastatic renal cell carcinoma within liver focal nodular hyperplasia (FNH) is reported here. The initial CT scan was classic for liver FNH yet the following liver resection showed a microscopic metastatic renal cell carcinoma (0.48 cm) within the liver nodule. FNH in a patient with existing primary tumor probably warrants further investigation as the coexistence of metastatic disease may significantly alter treatment. The high arterial blood flow in the liver FNH may predispose the region to develop a metastatic tumor. Also possible is that a metastatic tumor may cause a local vascular flow abnormality which induces hepatocellular hyperplasia, resulting in a secondary FNH.