[Metanephric adenoma. A new embryonal tumor of the kidney]

Metanephric adenoma is a kidney tumour first identified in 1988 and classified within the group of nephroblastic tumours. It is described as a benign tumour with no capacity to become malignant or metastatic, predominant in women in a 2:1 ratio relative to men, and which can develop at any point in life. In most cases, it is incidentally found as a result of an abdominal ultrasound study for signs and symptoms unrelated to the kidney. Less commonly it presents with pain, polycythemia, haematuria or palpable mass. The key radiologic sign is calcification, which occurs in a statistically higher proportion than in any other renal neoplasia. From the pathoanatomical point of view, the tumour consists of small acinus separated by acellular stroma resembling the hamartomatous elements of nephroblastomatosis and Wilms' tumour. This paper contributes one case of metanephric adenoma, the first one in the national literature.