Diagnostic puncture in renal cystic dysplasia (multicystic kidney). Evidence on the aetiology of the cysts.

Five cases of cystic dysplastic (multicystic) kidney occurring in infancy are described, in whom diagnostic puncture was used to confirm the suspected diagnosis. The characteristic finding on contrast injection was that the cystic spaces communicated via tubular structures, presumably nephronic, so ruling out the possibility of hydronephrosis. This finding also supports the view that cysts in multicystic kidney derive from nephrons and are not due to dilated calices. Although urography and ultrasonography both give appearances highly suggestive of multicystic kidney, the appearances on renal puncture are pathognomonic. When such appearances are demonstrated there is no urgent need for operative removal, except when necessitated by the size of the mass.