Correct answer: Extensive ground glass abnormality (extent > reticular abnormality) speaks against IPF. A usual interstitial pattern (UIP), which is characteristic of IPF, exhibits the following features:
Subpleural, basal predominance
Honeycombing with or without traction bronchiectasis
The presence of extensive ground glass abnormality (extent > reticular abnormality) is inconsistent with UIP pattern and should lead to an alternative diagnosis.
Raghu G, et al. An official ATS/ERS/JRS/ALAT statement: idiopathic pulmonary fibrosis: Evidence-based guidelines for diagnosis and management. Am J Respir Crit Care Med 2011;183(6):788-824.