[Medullary sponge kidney with severe renal function impairment: a case report].

: The term medullary sponge kidney refers as a renal parenchymal malformation characterized by cystic dilatation of the collecting ducts. Although medullary sponge kidney is a congenital disease, it is rarely identified in childhood and is usually discovered in adulthood. We report a child with bilateral medullary sponge kidney who, in addition to typical urographic findings, presented an unfavorable evolution that ended in renal chronic insufficiency. This outlook is uncommon and is described in only 10% of affected subjects.