[Diagnostic errors in nephroblastoma]

We review 37 patients diagnosed of Wilms' tumor at the Clinica Infantil "La Fe", in the last ten years, looking at the misdiagnosed cases. In two children, histological study showed a multilocular renal cyst. We also report a case previously diagnosed as being a multicystic kidney; the histological study revealed, however, a cystic partially differentiated nephroblastoma. No case of extrarenal tumors was present in the misdiagnosed patients. We comment the difficulties to make a correct diagnosis when confronted with the above mentioned entities and before histological data are available.