Malignant pleural effusion from metastatic prostate cancer: A case report with unusual cytologic findings

We present a case of 55-year-old man who complained of dyspnea and sputum for a month. He was an ex-smoker with a history of prostate cancer and pulmonary tuberculosis. Chest radiographs revealed bilateral pleural effusions of a small to moderate amount. Pigtail catheters were inserted for drainage. The pleural fluid consisted of large clusters and tightly cohesive groups of malignant cells, which however could not be ascribed to prostate cancer with certainty. We performed immunocytochemical panel studies to determine the origin of cancer metastasis. The immunostaining results were positive for prostate-specific antigen, alpha-methylacyl-coenzyme A racemase, and Nkx 3.1, consistent with prostate cancer. Pleural effusion associated with prostate cancer is rare. To our knowledge, this is the first case report in Korea to describe cytologic features of malignant pleural effusion associated with prostate cancer.