Urinothorax: an unexpected cause of severe dyspnea.

We report an unusual cause of the pleural effusion due to extravasation of urine from the retroperitoneal space into the thoracic cavity. In our case, the urinoma occurred owing to obstructing urinary tract lesion due to opaque stone. Although rare, urinothorax should be considered when pleural effusion occurs in patients with urinary tract obstruction accompanied by retroperitoneal urinoma.