A 55-year-old man presented to our institution with the chief complaint of slowly progressive exertional dyspnea over the preceding 5 weeks in conjunction with the loss of appetite and 10-kg weight loss. A chest computed tomography demonstrated a large mass in the right hemithorax. Characterization by magnetic resonance imaging revealed a massive 19.0 Â 13.8 Â 19.3 cm heterogeneously enhancing mass with slightly lobulated margins ( Figure A), and an F18-fluorodeoxyglucose positron emission tomography scan showed a heterogeneously fluorodeoxyglucose avid mass that filled the lower one half of the right thoracic cavity ( Figure B). Subsequently, transsternal resection of the huge tumor of the pleura was performed. Gross examination FIGURE. A, Thoracic MRI without and with intravenous contrast demonstrated 19.0 Â 13.8 Â 19.3 cm heterogeneously enhancing mass with slightly lobulated margins that occupies nearly the entire right hemithorax sparing the right upper lung. B, F18-FDG PET scan demonstrated heterogeneously moderate FDG uptake mass in the lower one half of the right thoracic cavity. C, Gross inspection revealed a 3530-g tan-yellow, focally necrotic mass that extends to involve the pleura and lung tissues. D, Microscopic findings showed a patternless architecture of alternating hypocellular and hypercellular areas of spindle-shaped cells consistent with a solitary fibrous tumor. FDG ¼ fluorodeoxyglucose; MRI ¼ magnetic resonance imaging; PET ¼ positron emission tomography.