Malignant Pleural Effusion from Metastatic Prostate Cancer: A Case Report with Unusual Cytologic Findings

Abstract

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.

Keywords: Neoplasm metastasis; Pleural effusion, malignant; Prostatic neoplasms.

Fig. 1.

Radiologic findings of the patient. (A) The tumor appears to replace most of the prostate and spread to perirectal area and bilateral pelvic wall on contrast-enhanced computed tomography. Extensive regional lymphadenopathy is observed (arrow). The chest X-ray reveals bilateral pleural effusions of a small to moderate amount (B) with a larger amount on the right side (C).

Fig. 2.

Cytologic features of Papanicolaou smears (A–C), the cell block (D–F) and the result of immunocytochemical staining (G–I). (A) It shows a sheet-like cell group. (B) A large cell-cluster is noted, forming three-dimensional ball. Hyperchromatic nuclei and high nuclear to cytoplasmic ratio are also observed. (C) The tumor cells have coarse, finely granular and vesicular chromatin. (D) The majority are in tightly cohesive groups of cells. (E) Some groups have the glandular lumen-like structure with central necrosis. Tumor cells are immunopositive for prostate-specific antigen (F), alpha-methylacyl-coenzyme A racemase (G), and Nkx 3.1 (H). (I) They show negative immunoreactivity for cytokeratin 5/6.

Fig. 3.

The histological characteristics of transurethral resection of the prostate specimen. (A) The hematoxylin and eosin stained section shows a poorly differentiated carcinoma. (B) Lymphovascular invasion is observed with the tumor emboli forming well-demarcated ovoid masses.