[Acute pyelo-ureteral obstruction by an intrasinusal intra- and para-pyelic cyst. Apropos of 3 cases].

Parapyelic cysts are not uncommon. There is usually no clinical expression of these cysts although development within the sinus can cause obstruction leading to acute nephretic colic. We observed two cases of intrasinus parapyelic cysts and another case of obstructive intrapyelic cyst. At ultrasonography, the only sign was hydronephrosis and a junction syndrome could not be eliminated. Intravenous pyelography demonstrated hydronephrosis and in one case a round intrapyelic mass. Computed tomography was required for diagnosis. Surgical exeresis was required due to the pain and compression damage to the parenchyma. This is a rare indication for surgical treatment of simple cysts of the kidney.