Renal metanephric adenoma mimicking papillary renal cell carcinoma on computed tomography: a case report.

We present a case of renal metanephric adenoma (MA) mimicking papillary renal cell carcinoma (PRCC) on computed tomography (CT). In the present case, double-phase enhanced CT showed a hypovascular right renal tumor with gradual and prolonged enhancement. The renal tumor was surgically removed. Histological examination of the resected specimen showed renal MA. Although the radiological features of renal MA have been described by some authors, only a few reports have mentioned the pattern of enhancement on multiphase enhanced CT. The pattern of enhancement of a renal tumor is likely to be correlated with its pathological features. Since renal MA is thought to be genetically related to PRCC, these two tumors are likely to demonstrate similar radiological features, so that differentiating between them becomes difficult. In patients with a hypovascular renal mass that shows gradual and prolonged enhancement on multiphase enhanced CT, the diagnosis of renal MA should be considered.