Nonspecific interstitial pneumonia (NSIP) can be idiopathic or a manifestation of collagen vascular diseases, hypersensitivity pneumonitis and drug-induced lung disease.

HRCT is the best imaging tool for characterization and assessment of disease extent. The main CT findings are: bibasilar ground-glass opacities and reticular opacities associated with traction bronchiectasis/bronchiolectasis, sometimes with subpleural sparing.

It is important to make the distinction from usual interstitial pneumonia, because NSIP has a better prognosis.