Metastatic Pleural Effusion: An Unusual Presentation of Urothelial Bladder Carcinoma.

Pleural effusions are frequently encountered in clinical practice. In the United States, malignancy is the third leading cause of pleural effusion after heart failure and pneumonia. The most common cause of malignant pleural effusion (MPE) is lung cancer, followed by breast cancer, lymphoma, and mesothelioma. Genitourinary cancers rarely metastasize to the pleura. Although several atypical patterns of thoracic metastasis from genitourinary cancers have been described in the literature, genitourinary cancers rarely give rise to MPEs. We describe a case where the workup of a unilateral pleural effusion led to the diagnosis of high-grade urothelial bladder carcinoma.