Lymphoproliferative diseases

Lymphoreticular diseases affecting the lung include primary and secondary lymphomas and related disorders, leukemias, and a number of lesions that are generally considered benign and hyperplastic processes. Distinguishing neoplastic disorders such as low-grade B-cell lymphomas from reactive conditions associated with prominent lymphoid infiltrates such as lymphocytic interstitial pneumonia has long been difficult for pathologists.1-4 This difficulty is typified by the colorful history of pseudolymphoma (see below) and by lymphomatoid granulomatosis, with all its synonyms,5-7 which has been considered by some to be a peculiar vasculitis and by others a lymphoproliferative disorder, although the weight of evidence suggests that most cases represent the latter.8