Sonographic features of renal obstruction mimicked by peripelvic cysts.

Peripelvic cysts can closely mimic the sonographic changes of renal pelvicalyceal dilatation. Three cases are described in which a particular feature was the presence of linear septations extending to the hilum which represented the walls of tubular peripelvic cysts. The cluster of cysts centrally in the renal sinus was originally interpreted as a dilated pelvicalyceal system. Excretion urography is usually necessary to exclude pelvicalyceal dilatation conclusively.