Perirenal hemorrhage as first presentation of Wilms tumor.

Wilms tumor typically presents as an abdominal mass, though occasionally patients present with other manifestations. We report a case of a child presenting with a perirenal hemorrhage and an initially occult Wilms tumor, found only on subsequent renal arteriography. Symptoms in this patient were caused by the presence of perirenal and subcapsular hemorrhage rather than the tumor itself. Despite an unusual presentation, we need to consider underlying neoplasia in children with renal hemorrhage and the absence of a history of trauma. Follow-up studies might help clarify initial negative imaging results.