Imaging Findings

(A) Frontal chest radiograph demonstrates a large, well-circumscribed mass in the left upper chest (arrow). There is no evidence of rib destruction. (B) Lateral chest radiograph confirms the smooth inferior margin of the mass (arrow); however, the precise location of the abnormality cannot be determined. (C) Noncontrast computed tomography (soft-tissue windows) shows that the mass has heterogeneous density. It forms obtuse angles with the pleura, suggesting an extrapulmonary location (arrow). (D) T2-weighted magnetic resonance imaging (MRI) shows that the mass has heterogeneous but predominantly high signal intensity and multiple hypointense septa (arrow).