Details
Right renal mass.
Metanephric adenoma is a rare tumour of the kidney which demonstrates features reminiscent of metanephric tubular differentiation during embryogenesis. These tumours are found in individuals over a large age range and exhibit benign behaviour.
As seen in this case, metanephric adenomas are typically unencapsulated and circumscribed without causing significant mass related effects on the adjacent kidney parenchyma. The tumour is composed of crowded tubules of uniform primitive appearing cells which have scant cytoplasm and round to oval nuclei with grooves and/or folds.
The morphologic features of metanephric adenomas are often characteristic; however, they may be mistaken for papillary renal cell carcinoma or epithelial predominant Wilms tumour.