Benign metanephric tumor

A rare renal tumor characterized by a benign epithelial (metanephric adenoma), biphasic (metanephric adenofibroma) or renal stromal (metanephric stromal tumor) neoplasm. Metanephric adenoma mostly occurs in the fifth to sixth decade of life with distinct female predominance. It may be asymptomatic or present with abdominal pain, hematuria, and/or polycythemia. Metanephric adenofibroma has been described from infancy to young adulthood, potentially causing polycythemia or hematuria. Metanephric stromal tumor typically presents in infancy or childhood as an abdominal mass, sometimes manifestations of extrarenal vasculopathy such as hypertension or hemorrhage.