A 63-Year-Old Man With Recurrent Dyspnea

A 63-year-old man presented with a 12-month history of recurrent dyspnea, dry cough, fatigue, and weight loss. He denied chest pain, fever, or chills. Chest radiographs during those months revealed bilateral pleural effusions, and he was subjected to serial thoracenteses. Pleural fluid analyses suggested invariably a transudate, and he had received an empirical antiheart failure regimen for several months. However, his symptoms did not improve. He reported no smoking or alcohol use and his medical history was unremarkable.