Table 5.
Selected Fibrotic Lung Diseases That Can Manifest Progressive Pulmonary Fibrosis
| Potentially Fibrotic Interstitial Lung Diseases | Histologic Patterns |
|---|---|
| Idiopathic F-NSIP | • F-iNSIP (179) |
| PPFE | • IAFE (179) • May coexist with other patterns such as UIP in patients with other forms of concomitant ILD (e.g., IPF) (180) |
| FOP | • Cicatricial organizing pneumonia (181) • Organizing pneumonia with concomitant interstitial fibrosis (sometimes secondary to diffuse alveolar damage/acute interstitial pneumonia) (179, 182) |
| DIP | • DIP* |
| Fibrotic CTD-related ILD | • F-NSIP, FOP, UIP (use histopathological criteria for idiopathic diseases [179]) |
| Fibrotic HP | • HP and probable HP (138) • Fibrotic element may be that of UIP, F-NSIP, or bronchiolocentric fibrosis |
| Fibrotic occupational ILD | • Dependent on occupational lung disease (asbestosis, fibrotic HP, silicosis, pneumoconiosis, or other) (183) |
| Fibrotic LCH | • F-LCH (184) |
| Fibrotic sarcoidosis | • Discrete nonnecrotizing granulomas with a lymphatic distribution with coexistent fibrosis (185) |
| Unclassified fibrotic ILD | • Cases should ideally be termed “unclassifiable” only after multidisciplinary discussion. Most cases represent combined or overlapping patterns of classifiable interstitial pneumonias, and these should be reported as such (179) |
| Other | • Fibrosis in association with inborn errors of metabolism, surfactant protein disorders, pulmonary involvement by systemic disorders, or others |
Definition of abbreviations: CTD = connective tissue disease; DIP = desquamative interstitial pneumonia; F-LCH = fibrotic Langerhans cell histiocytosis; F-iNSIP = fibrotic idiopathic nonspecific interstitial pneumonia; F-NSIP = fibrotic nonspecific interstitial pneumonia; FOP = fibrosing organizing pneumonia; HP = hypersensitivity pneumonitis; IAFE = intraalveolar fibrosis and elastosis; ILD = interstitial lung disease; IPF = idiopathic pulmonary fibrosis; LCH = Langerhans cell histiocytosis; PPFE = pleuroparenchymal fibroelastosis; UIP = usual interstitial pneumonia.
Terminology for fibrotic interstitial pneumonias with DIP-like features is controversial, this overlapping with F-NSIP.