Objective: To explore the etiology, diagnosis and differential diagnosis of lymphocytic interstitial pneumonia (LIP).
Method: The clinical, radiographical and histological characteristics of three cases of LIP diagnosed in Peking Union Medical College Hospital were analyzed, and the literature was reviewed.
Results: The precise cause of LIP was unknown. However, LIP was strongly associated with autoimmune diseases and immunodeficiency. Clinically, patients presented with chronic cough and progressive dyspnea. Pulmonary function tests showed restrictive ventilatory pattern. HRCT of chest revealed ground-glass attenuation, centrilobular nodules, subpleural small nodules, thickening of bronchovascular bundles, interlobular septal thickening and cystic dilated air spaces. Bronchoalveolar lavage showed an increase in lymphocytes. The key finding in histopathology was dense interstitial lymphoid infiltrate with a polyclonal pattern.
Conclusion: Idiopathic LIP is rare. Cases of LIP should be thoroughly investigated for any known causes and related disorders.