Urinothorax: an unexpected cause of pleural effusion in a patient with non-Hodgkin lymphoma.

Urinothorax is a rather rare cause of pleural effusion and its potential mechanism is urinary tract obstruction or trauma that results in urine leakage and accumulation inside the pleural space. Patients with non-Hodgkin lymphoma could present with pleural effusion due to mediastinal lymphadenopathy or extrathoracic manifestation such as urinary tract obstruction, the latter described in our case report. Physicians must be aware even of the more occult mechanisms of pleural fluid accumulations which could point to extrathoracic manifestations of involvement.