Lymphocytic infiltrations of the lung

Lymphocytic infiltrations of the lung arise from the proliferation of bronchus-associated lymphoid tissue, resulting in a spectrum of rare conditions ranging from benign polyclonal lymphoid interstitial pneumonia to monoclonal primary malignant lymphomas of the lung. Lymphoid interstitial pneumonia is most commonly seen in Sjögren’s syndrome or other connective tissue diseases, and in association with HIV infection, and is characterized by reticulonodular shadowing on CT imaging and (usually) a good response to corticosteroids. Primary pulmonary lymphomas fall into three categories: lymphomatoid granulomatosis, low-grade B-cell lymphoma, and high-grade B-cell lymphoma. The latter require treatment with cytotoxic drugs and have a poor prognosis.