Figure 13. Lipoma in a 42-year-old woman. Axial contrast-enhanced CT scan at the level of the pulmonary artery (P) shows a well-defined mass with the same attenuation as fat in the left part of the chest wall. Soft-tissue septa (arrows) are clearly visible at the periphery of the mass. Septa not only occur in benign lipomas but also are common in atypical lipomatous tumors and liposarcomas.