- Adult patients with newly detected interstitial lung disease (ILD) of apparently unknown cause are clinically suspected of having idiopathic pulmonary fibrosis (IPF) if they have unexplained symptomatic or asymptomatic patterns of bilateral fibrosis on a chest radiograph or chest computed tomography (CT) scan, bibasilar inspiratory crackles, and an age typically older than 60 years.
- Rarely, middle-aged adults (>40 yr and <60 yr), especially those with risks for familial pulmonary fibrosis, may otherwise manifest the same clinical scenario as the typical patient older than 60 years.
- The recommendations in this guideline are for the patterns and distributions of images obtained by high-resolution CT (HRCT) imaging and, thus, require that patients be subjected to HRCT of the chest for evaluation.
Diagnostic Criteria for IPF
- Exclusion of other known causes of ILD (e.g., domestic and occupational environmental exposures, CTD, drug toxicity), and either #2 or #3:
- The presence of the HRCT pattern of UIP (Table 3)
- Specific combinations (Figure 8) of HRCT patterns (Table 3) and histopathology patterns (Table 4) in patients subjected to lung tissue sampling
Table 1. Comparison of ATS/ERS/JRS/ALAT Recommendations for the Diagnosis of IPF in the 2011 and 2018 Guidelines
|HRCT Pattern of Probable UIP, Indeterminate for UIP, and Alternative Diagnosis||HRCT Pattern of UIP||2011 Guideline: Did Not Distinguish among Patients with Different HRCT Patterns|
|BAL cellular analysis||We suggest performing BAL cellular analysis (C)||We suggest NOT performing BAL cellular analysis (C)||BAL cellular analysis should not be performed in the diagnostic evaluation of IPF in the majority of patients, but may be appropriate in a minority of patients.|
|Surgical lung biopsy||We suggest performing surgical lung biopsy (C)||We recommend NOT performing surgical lung biopsy (S)||Surgical lung biopsy is not required for patients with an HRCT pattern consistent with UIP.|
|Transbronchial lung biopsy||No recommendation for or against||We recommend NOT performing transbronchial lung biopsy (S)||Transbronchial biopsy should not be used in the evaluation of IPF in the majority of patients, but may be appropriate in a minority.|
|Lung cryobiopsy||No recommendation for or against||We recommend NOT performing cryobiopsy (S)||Not addressed|
|Medical history of medication use and environmental exposures||We recommend taking a detailed history of both medication use and environmental exposures at home, work, and other places the patient frequently visits to exclude potential causes of ILD (motherhood statement)||Diagnosis of IPF requires exclusion of other known causes of ILD (e.g., domestic and occupational environmental exposures, connective tissue disease, and drug toxicity).|
|Serological testing to exclude connective tissue disease||We recommend serological testing to exclude connective tissue diseases as a potential cause of the ILD (motherhood statement)|
|Multidisciplinary discussion||We suggest multidisciplinary discussion for decision-making (C)||We recommend that a multidisciplinary discussion should be used in the evaluation of IPF.|
|Serum biomarkers||We recommend NOT measuring serum MMP-7, SPD, CCL-18, or KL-6 for the purpose of distinguishing IPF from other ILDs (S)||Not addressed|
S= strong recommendation; C = conditional recommendation.
Table 2. High-Resolution CT Scanning Parameters
|Recommended Scanning Protocol||Advantages of Updated Recommendations|
Table 3. High-Resolution CT Scanning Patterns
|UIP||Probable UIP||Indeterminate for UIP||Alternative Diagnosis|
|Subpleural and basal predominant; distribution is often heterogeneousa|
Honeycombing with or without peripheral traction bronchiectasis or bronchiolectasisb
|Subpleural and basal predominant; distribution is often heterogeneous|
Reticular pattern with peripheral traction bronchiectasis or bronchiolectasis
May have mild GGO
|Subpleural and basal predominant|
Subtle reticulation; may have mild GGO or distortion ("early UIP pattern")
CT features and/or distribution of lung fibrosis that do not suggest any specific etiology ("truly indeterminate")
|Findings suggestive of another diagnosis, including:|
b Superimposed CT features: mild GGO, reticular pattern, pulmonary ossification.
Figure 1. High-Resolution CT Images Demonstrating a Usual Interstitial Pneumonia Pattern
(A–C) Transverse CT section and (D) coronal reconstruction illustrating the presence of honeycombing with subpleural and basal predominance. Note the concurrent presence of mild groundglass opacity. (E) Magnified view of the left lower lobe showing typical characteristics of honeycombing, consisting of clustered cystic airspaces with well-defined walls and variable diameters, seen in single or multiple layers (arrows).