Pulmonary interstitial lymphocyte infiltration Diffuse pulmonary lymphoid hyperplasia 2023-07-01T16:44:28Z Diffuse lymphoid hyperplasia (DLH) describes the pathological entity that lies between follicular bronchiolitis and lymphocytic interstitial pneumonia (LIP). It is pathologically characterized by a diffuse peribronchiolar proliferation of hyperplastic lymphoid follicles (BALT), extended along the lymphatics to involve the interlobular septa and pleura. Unlike LIP, DHL does not show uniform involvement of the alveolar septa.