Seminars in respiratory and critical care medicine
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Semin Respir Crit Care Med · Aug 2001
Lymphocytic interstitial pneumonia and other lymphoproliferative disorders in the lung.
Lymphocytic interstitial pneumonia (LIP) is a clinicopathologic term that relates histologically to a dense interstitial infiltrate of mainly T cells, plasma cells, and histiocytes, with germinal centers often identified. Its precise etiology is unknown, but there are strong clinical associations with several autoimmune disorders, as well as both congenital and acquired immunodeficiency syndromes. ⋯ LIP may also be histologically indistinguishable from nodular lymphoid hyperplasia and lymphomas arising from mucosa-associated lymphoid tissue (MALT) but can usually be differentiated via analysis of clinical and imaging data plus assessment of immunohistochemistry and gene rearrangement studies. Other entities include lymphomatoid granulomatosis, intravascular lymphomatosis, Castleman's disease, primary pleural lymphomas, primary effusion lymphomas, plasmacytomas, and secondary involvement by lymphoma, but these should all be readily distinguishable from lymphocytic interstitial pneumonia if all clinical, imaging, and histological data are apparent.
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Usual interstitial pneumonia (UIP) is a distinct histological lesion observed in idiopathic pulmonary fibrosis (IPF), but can be found in other etiologies. The diagnosis of UIP can be established by surgical lung biopsy or by high resolution thin section computed tomographic scans (provided the radiographic features are classical). Historically, patients labeled as "IPF'' encompassed a group of disorders including UIP as well as other idiopathic interstitial pneumonias, which differ from UIP in prognosis and responsiveness to therapy. ⋯ Single-lung transplantation is a viable option for patients failing medical therapy. Novel therapeutic strategies based upon inhibiting fibroproliferation or enhancing alveolar reepithelialization are desperately needed. In this article, we discuss diagnostic criteria for UIP (both histopathological and radiographic), natural history and clinical course, and therapeutic approaches (both current and future).