Extrapleural fat collections: pseudotumors and other confusing manifestations.

Because thoracic fat is mobile and plastic, it can assume a variety of shapes and distributions. Fat collections can be confusing, and some can even mimic tumors. This essay highlights the variable and potentially confusing manifestations of normal thoracic fat on plain radiographs and CT scans. It does not emphasize fatty tumors, ordinary mediastinal lipomatosis, costal fat pads, or diaphragmatic hernias, as these topics have been reviewed recently.