Diagnostic components for idiopathic pulmonary fibrosis (IPF)

ATS/ERS/JRS/ALAT clinical practice guideline [1]Fleischner white paper consensus statement [2]
Age limit for increased diagnostic confidence60 years
HRCT patternUIPTypical UIP
Subpleural and basal predominance
Presence of honeycombing with or without peripheral traction bronchiectasis
Biopsy not recommended
Probable UIP
Subpleural and basal predominance
Presence of peripheral traction bronchiectasis
Biopsy recommended (conditional)Biopsy not recommended
Indeterminate for UIP
Subpleural and basal predominantVariable or diffuse
May have mild GGO or distortionFeatures suggestive of non-UIP pattern
Biopsy recommended
Alternative diagnosisMost consistent with non-IPF diagnosis
Findings suggestive of another diagnosis
Biopsy recommended
Histopathology patternUIPDefinite UIP
Dense fibrosis with architecture remodelling
Predominant subpleural or paraseptal distribution of fibrosis
Patchy lung involvement by fibrosis
Presence of fibroblastic foci
Probable UIP
Honeycomb fibrosis only
Fibroblastic foci may or may not be present
Indeterminate for UIP
Fibrosis with or without architecture distortion
Some histological features from the UIP pattern
Occasional foci of centrilobular injury or scarring
Rare granulomas or giant cells
Minor degree of lymphoid hyperplasia or diffuse inflammation
Diffuse homogenous fibrosis favouring fibrotic nonspecific interstitial pneumonia
Alternative diagnosisFeatures most consistent with an alternative diagnosis
Histological findings indicative of other diseasesA UIP pattern with ancillary features strongly suggesting an alternative diagnosis
A non-UIP pattern

Criteria have been summarised for purposes of comparison. ATS: American Thoracic Society; ERS: European Respiratory Society; JRS: Japanese Respiratory Society; ALAT: Latin American Thoracic Society; HRCT: high-resolution computed tomography; UIP: usual interstitial pneumonia; GGO: ground-glass opacities.