Diaphragmatic and paradiaphragmatic tumors and pseudotumors.

Primary lesions of the diaphragm are rare and are often difficult to distinguish from a host of other entities. Primary tumors include lipomas, cysts, and sarcomas, while secondary lesions, which can mimic them, include direct extensions from neighboring organs or metastatic implants and adenopathy. In addition, one must exclude a variety of pseudotumors, such as eventrations, diaphragmatic invaginations, and crural thickening. Examples of such primary and nonprimary diaphragmatic lesions are discussed.