Abstract
Rationale: Although positively defined at pathology, NSIP can overlap with other patterns. NSIP is mainly idiopathic or associated with connective tissue diseases (CTDs) or chronic hypersensitivity pneumonitis (cHP).
Objectives: To separate NSIP into various pathologic sub-types and correlate them with clinical causes and survival.
Methods: 136 patients with surgical lung biopsy-proven NSIP were included (CTDs: 23%, cHP: 12%, idiopathic: 65%). In addition to the indisputable NSIP criteria, 7 sub-types were a priori set up based on pathologic superimposed minor features: UIP-like, cHP-like, OP-like, organizing DAD-like, DIP-like, LIP-like, and essential NSIP in the absence of discriminating feature. Biopsies were reviewed independently by 2 pathologists and a consensus was obtained.
Results: Inter-observer concordance was excellent (kappa=0.87), resulting in following consensus: UIP-like (26%), cHP-like (10%), OP-like (6%), organizing DAD-like (10%), DIP-like (7%), LIP-like (2%), essential NSIP (36%). Five cases were unclassifiable. OP-like pattern was linked with CTDs (p=0.04) and cHP-like pattern with a clinical diagnosis of cHP (p=0.02). Survival was significantly different between sub-groups (p=0.0002). Organizing DAD-like pattern showed the poorer survival (32% at 5 years), followed by UIP-like pattern (57% at 5 years). Independent predictors of mortality included organizing DAD-like pattern (HR: 4.99, 95%CI: 2.15-11.58, p=0.0002), UIP-like pattern (HR: 2.11, 95%CI: 1.12-3.99, p=0.02) and a clinical diagnosis of cHP (HR: 2.17, 95%IC: 1.05-4.47, p=0.035).
Conclusion: NSIP subdivision into discrete pathologic sub-types has a clinical relevance from a prognosis and causal perspective.
- © 2013 ERS
