Idiopathic nonspecific interstitial pneumonia: report of an American Thoracic Society project

Am J Respir Crit Care Med. 2008 Jun 15;177(12):1338-47. doi: 10.1164/rccm.200611-1685OC. Epub 2008 Apr 3.


Rationale: The 2002 American Thoracic Society/European Respiratory Society classification of idiopathic interstitial pneumonias identified nonspecific interstitial pneumonia (NSIP) as a provisional diagnosis. Concern was expressed that NSIP was a "wastebasket" category, difficult to distinguish from other idiopathic interstitial pneumonias.

Objectives: The following questions were addressed: (1) Is idiopathic NSIP a distinct entity? 2) If so, what are its clinical, radiologic and pathologic characteristics? (3) What is the role of radiology and pathology in establishing the diagnosis? (4) To make a diagnosis of idiopathic NSIP, what other disorders need to be excluded and how should this be done?

Methods: Investigators who had previously reported cases of idiopathic NSIP were invited to submit cases for review (n = 305). After initial review, cases with complete clinical, radiologic, and pathologic information (n = 193) were reviewed in a series of workshops.

Measurements and main results: Sixty-seven cases were identified as NSIP. Mean age was 52 years, 67% were women, 69% were never-smokers, and 46% were from Asian countries. The most common symptoms were dyspnea (96%) and cough (87%); 69% had restriction. By high-resolution computed tomography, the lower lung zones were predominantly involved in 92% of cases; 46% had a peripheral distribution; 47% were diffuse. Most showed a reticular pattern (87%) with traction bronchiectasis (82%) and volume loss (77%). Lung biopsies showed uniform thickening of alveolar walls with a spectrum of cellular to fibrosing patterns. Five-year survival was 82.3%.

Conclusions: Idiopathic NSIP is a distinct clinical entity that occurs mostly in middle-aged women who are never-smokers. The prognosis of NSIP is very good.

Publication types

  • Consensus Development Conference
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adult
  • Aged
  • Diagnosis, Differential
  • Female
  • Humans
  • Lung Diseases, Interstitial / diagnosis*
  • Lung Diseases, Interstitial / diagnostic imaging
  • Lung Diseases, Interstitial / epidemiology
  • Lung Diseases, Interstitial / pathology
  • Male
  • Middle Aged
  • Prognosis
  • Sex Distribution
  • Survival Rate
  • Tomography, X-Ray Computed