Urinothorax: report of 4 cases and review of the literature.

Urinothorax should be considered when pleural effusion occurs in patients with urinary tract obstruction accompanied by retroperitoneal urinoma. This recommendation is based on our experience with 4 cases and a review of the literature. In 2 patients urinary obstruction was owing to retroperitoneal fibrosis secondary to malignancy, including one who had a neuroectodermal undifferentiated small round cell tumor and the other who had a metastatic epithelial neoplasm. In the 2 other patients urinary obstruction resulted from a failed ureteroneocystotomy following renal allograft transplantation. All 4 patients had a urinoma, which may be a predisposing factor to urinothorax.