HRCT Findings of Nonspecific Interstitial Pneumonia (NSIP)

Primary HRCT Features

• Bilateral ground-glass opacity is the most common HRCT abnormality in NSIP, present in the vast majority of cases 1
• Irregular reticular opacities occur in approximately 75% of NSIP cases 1
• Traction bronchiectasis and bronchiolectasis are present in approximately 75% of cases 1

Distribution Patterns

• Subpleural sparing is a helpful distinguishing feature from UIP 1, 2, 3
• Bilateral, symmetric involvement with basal predominance 1

Key Distinguishing Features from UIP

• Honeycombing is sparse or absent at presentation in NSIP 1
• Honeycombing may increase in prevalence during follow-up in some NSIP cases 1

Additional HRCT Findings

• Consolidation may be present, reflecting an organizing pneumonia component, which may suggest connective tissue disease 1

Diagnostic Accuracy and Clinical Implications

• Extensive ground-glass opacification with subpleural sparing on HRCT suggests an alternative diagnosis to IPF and should prompt consideration of fibrotic NSIP 2, 3
• When HRCT patterns are atypical or mixed, multidisciplinary discussion integrating clinical, radiological, and pathological findings is essential 1