Rare localization of extrarenal nephroblastoma in 1-month-old female infant.

Extrarenal occurrence of Wilms' tumor is exceptional and the diagnosis is almost always made after surgery. The exact mechanism whereby a Wilms' tumor occurs in extrarenal tissue is unknown. The tumor is most commonly located in the retroperitoneum or inguinal region. Localization in subcutaneous tissue is extremely rare. In this paper, the case of a 1-month-old female infant with an extrarenal Wilms' tumor located in the lumbosacral region is presented. Surgical excision is the treatment of choice, and the same general therapeutic rules should be followed as when the kidney is affected.