Pulmonary lymphomas: current concepts.

The shift from a clinical definition (aggressive behavior) to an immunologic definition (clonal proliferations of cells) of lymphomas has led to a reinterpretation of most pulmonary pseudolymphomas as indolent lymphomas. The recognition of the diverse histologic appearance of lymphomas and the acceptance of extranodal lymphomas support the view that most cases of lymphomatoid granulomatosis are malignant lymphomas. Criteria for the recognition and classification of pulmonary lymphoid lesions are discussed.