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E1818. Pulmonary Lymphoproliferative Disorders Updated: Current Understanding of Old Diseases
Authors
  1. Michal Gabbai; University of Pennsylvania
  2. Rosita Shah; University of Pennsylvania
  3. Ana Kolansky; University of Pennsylvania
Background
Pulmonary lymphoproliferative diseases include reactive, proliferative and neoplastic lymphatic infiltration in response to viral or immunologic stimuli, in at-risk patients who frequently have a history of immune-suppression or collagen vascular disease. With a greater understanding of molecular biology, the lymphoproliferative spectrum currently includes entities that were previously thought to be idiopathic (IgG4 disease, granulomatous lymphocytic interstitial lung disease), or representative of unrelated or unrecognized malignancies (multicentric Castleman disease, lymphomatoid granulomatosis, pleural effusion lymphoma). Protean manifestations in the thorax can lead to delayed diagnosis, and include fibrosis which can result in progressive lung destruction, often not recognized as a feature of lymphoproliferative disease. Furthermore, the same at risk population is subject to chronic airway and infiltrative interstitial diseases, such that correctly identifying features of lymphoproliferative disease can initiate the correct workup and help avoid delayed recognition of lymphatic malignancy.

Educational Goals / Teaching Points
Chronic lymphocytic infiltration of the lung parenchyma leads to imaging abnormalities that are often incorrectly diagnosed as primary airway and interstitial disease. This exhibit will detail 1. the lymphatic anatomy and physiology of the lung and 2. the imaging findings associated with expansion of these spaces, with the goal of improving early recognition of the lymphoproliferative disorders and expediting the diagnosis of associated lymphatic malignancies in at risk patients. The risk factors and associations with pulmonary lymphoid proliferation and neoplastic transformation are reviewed, including auto-immune diseases, chronic immune-suppression associated with HIV and post-transplant settings, and oncogenic/lymphocytotrophic viral infection. The participant in this exhibit will also become familiar with the fibrogenic features of the non-neoplastic lymphoproliferative diseases and imaging findings that favor malignancy.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
This exhibit reviews the anatomy and physiology of the cellular, lymphatic and nodal compartments of the lung and imaging abnormalities resulting from infiltration of the various compartments, often leading to findings that mimic airway and interstitial disease, including fibrosis. Current understanding of the molecular and immunologic factors that are associated with pulmonary lymphoid proliferation, neoplastic transformation and chronic fibrogenesis are reviewed.

Conclusion
While characterized by lymphocytic infiltration, the pulmonary lymphoproliferative disorders consist of heterogeneous clinical entities in which radiographic assessment is relevant to initial detection and initiation of the appropriate clinical workup. A greater understanding of lymphocyte molecular biology and the role of chronic immune stimulation and suppression has resulted in recognition of new neoplastic and chronic inflammatory, potentially fibrogenic diseases that fall into the spectrum of lymphoproliferative disease of which the radiologist must be aware.