Traditionally, a subset of patients diagnosed as having idiopathic pulmonary fibrosis had positive results on cellular biopsies (prominent lymphoplasmacytic inflammation), bronchoalveolar lavage lymphocytosis, a clinical response to steroids, and a better long-term prognosis. On review of the lung histopathology, the lesion was characterized by varying degrees of inflammation and fibrosis. This entity is now recognized as a distinct entity among idiopathic interstitial pneumonias.