A Case of Malignant Pleural Effusion Due to Urothelial Carcinoma

Abstract

　Malignant pleural effusion is characterized by fluid buildup between the lung and the chest wall due to cancer cells in the pleura. Most cases are caused by lung cancer, breast cancer, ovarian cancer, or malignant lymphoma. Urothelial carcinoma is a rare cause of malignant pleural effusions and is difficult to diagnose by cytological examination. We report a case of malignant pleural effusion due to urothelial carcinoma. An 80-year-old man presented with right back pain. After close examination, he was diagnosed with ureteral cancer. During the course of treatment, a unilateral pleural effusion was found, and cytological and histological examinations were performed on suspicion of malignant pleural effusion. Cytological examination revealed numerous round-to-ovoid cells with irregularly enlarged nuclei. Immunohistological studies were performed on cell block specimens, and urothelial carcinoma was diagnosed. Cytological examination of malignant pleural effusions may require estimation of the primary site. It is important to take a multifaceted approach that considers not only the cytological findings but also the clinical findings and medical history.