<unk>  refers to collection of urine between the pleural layers.  It is a rare case of pleural effusion secondary to obstructive uropathy whereby urine forms a collection in the pleural cavity.  The urine arrives in the pleural space either retroperitoneally under the posterior diaphragm, or via the retroperitoneal lymphatics.  It remains a rare and possibly under-diagnosed differential in the case of transudative pleural effusion.
Handa et al described 47 cases between 1967 and 2007, noting that it was more prevalent in males, generally ipsilateral to the obstruction, and in most cases relieved by clearance of the obstruction.
Urinothorax
Hemothorax
Chylothorax
Hydropneumothorax
Hemopneumothorax
Pulmonary hematoma
Round pneumonia
Pneumothorax