Heterogeneity of pulmonary fibrosis: interstitial pneumonias and sarcoidosis

This review focuses on two representatives of pulmonary fibrosis. One is usual interstitial pneumonia lesion, typically seen in patients with idiopathic pulmonary fibrosis. The other is parenchymal fibrosis along the bronchovascular bundles, observed in patients with sarcoidosis. Both are intractable fibrosis amenable only to lung transplantation. The authors trace the historical classification of idiopathic interstitial pneumonia, discuss interstitial pneumonia associated with collagen vascular diseases and occupational exposure, and review the most important issues to clarify both types of pulmonary fibrosis.