Lymphocytic interstitial pneumonia

Imaging description The primary imaging findings of lymphocytic interstitial pneumonia (LIP) are bilateral regions of ground-glass opacity [1, 2]. These are most often diffuse, but may be patchy in distribution. Most patients will also have poorly defined centrilobular nodules. Thickening of interlobular septa and bronchovascular bundles is present in 80% of patients. Small subpleural nodules are also seen in nearly 80% of patients. Parenchymal cysts are present in roughly two-thirds of all patients (Figures 15.1 and 15.2). Pleural effusions are rare. Importance Lymphocytic interstitial pneumonia in the adult is a benign disorder characterized by infiltration of the pulmonary interstitium by lymphocytes and plasma cells [1, 2]. LIP is characteristically steroid responsive.