Urine in the lung: An uncommon cause of transudative pleural effusion.

Urinothorax [UT], the accumulation of urine in the pleural space, is an uncommon cause of pleural effusions resulting from trauma, obstruction, or iatrogenic causes. Thoracentesis with pleural fluid analysis and evaluation of biochemical characteristics, such as pleural fluid creatinine (PCr) to serum creatinine ratio (Scr), is necessary to establish this diagnosis. This case illustrates a 93 year old man with a complicated past medical history including chronic kidney disease stage 4, adenocarcinoma of the prostate status post brachytherapy complicated by proctitis, high grade transitional cell carcinoma of the right kidney with right hydronephrosis, and recurrent hematuria who was hospitalized for worsening hematuria and suprapubic pain.