True Hemothorax as the Initial Presentation of Prostate Adenocarcinoma with Pleural Metastasis: A Case Report.

True hemothorax as an initial manifestation of prostate cancer has not yet been reported. An adult male presented with acute right-sided pleural effusion. Diagnostic thoracentesis yielded hemorrhagic pleural fluid, with a pleural fluid hematocrit ≥ 50% of the peripheral blood hematocrit, confirming hemothorax. Contrast-enhanced computed tomography revealed prostate enlargement, pulmonary nodules, and pleural masses. Transbronchial biopsies of the pulmonary nodule confirmed metastatic adenocarcinoma positive for prostate-specific antigen and negative for thyroid transcription factor-1, thus establishing the diagnosis of metastatic prostate adenocarcinoma. Androgen deprivation therapy improved the hemothorax. Bloody pleural effusion warrants hematocrit measurement and evaluation for malignancy, including metastatic prostate cancer.