Lung fibrosis: new classifications and therapy

Area of Science:

• Pulmonology
• Rheumatology
• Pathology

Background:

• The American Thoracic Society/European Respiratory Society (ATS/ERS) classification of idiopathic interstitial pneumonia (IIP) is relevant for pulmonary fibrosis in connective tissue disease (CTD).
• Usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) are the primary histopathologic patterns observed.
• NSIP is more prevalent than UIP in systemic sclerosis (SSc).

Purpose of the Study:

• To review the applicability of the ATS/ERS classification to CTD-associated pulmonary fibrosis.
• To discuss the prevalence, prognostic significance, and therapeutic approaches for UIP and NSIP in CTD.

Main Methods:

• Review of recent literature on interstitial pneumonia classification and treatment in CTD.
• Analysis of histopathologic findings and computed tomography (CT) imaging in distinguishing UIP from NSIP.
• Evaluation of therapeutic strategies for UIP and NSIP in the context of CTD.

Main Results:

• The ATS/ERS classification is applicable to CTD-associated pulmonary fibrosis, with NSIP being more frequent than UIP in SSc.
• The prognostic significance of NSIP in CTD remains unclear, though it generally carries a better prognosis than UIP in IIP.
• Computed tomography (CT) requires further refinement for accurate differentiation between UIP and NSIP.
• Corticosteroid and immunosuppressive therapies show limited efficacy in UIP, shifting focus towards antifibrotic agents.
• Cyclophosphamide demonstrates therapeutic benefit in progressive lung fibrosis associated with SSc.

Conclusions:

• The ATS/ERS classification provides a framework for understanding pulmonary fibrosis in CTD.
• Therapeutic strategies for UIP and NSIP in CTD should be distinct, with antifibrotics for UIP and continued consideration of cyclophosphamide for SSc-related fibrosis.
• Further research is needed to clarify the prognosis of NSIP in CTD and refine CT imaging for UIP/NSIP distinction.