Interstitial Lung Disease: A Practical Treatment Guide for Pulmonologists

Interstitial lung diseases (ILDs) encompass over 200 distinct disorders characterized by inflammation and fibrosis of the lung interstitium. This guide provides a practical framework for diagnosing and managing the most common ILD subtypes.

Classification and Diagnostic Approach

ILDs are broadly classified into: (1) idiopathic interstitial pneumonias (IIPs), with idiopathic pulmonary fibrosis (IPF) being the most common; (2) connective tissue disease-associated ILD (CTD-ILD); (3) hypersensitivity pneumonitis (HP); (4) drug-induced ILD; and (5) sarcoidosis. A systematic diagnostic approach combining clinical history, HRCT patterns, and multidisciplinary discussion is essential.

Idiopathic Pulmonary Fibrosis (IPF)

IPF is a chronic, progressive fibrotic lung disease with a median survival of 3-5 years post-diagnosis. Two antifibrotic agents — nintedanib and pirfenidone — are approved and slow disease progression by approximately 50% as measured by FVC decline. Both are recommended for patients with mild to moderate IPF (FVC > 50% predicted).

CTD-Associated ILD

CTD-ILD management depends on the underlying autoimmune condition. For rheumatoid arthritis-ILD and scleroderma-ILD, immunosuppression with mycophenolate mofetil or cyclophosphamide remains the mainstay, with antifibrotics emerging as an option for progressive fibrosing phenotypes.

Hypersensitivity Pneumonitis

Identification and complete avoidance of the offending antigen is the cornerstone of treatment. Corticosteroids are used for acute flares and progressive disease. Chronic HP with fibrosis may require longer immunosuppression or antifibrotic therapy.

When to Refer for Transplant

Early referral for lung transplant evaluation is recommended for IPF patients with declining FVC, increasing oxygen requirements, or progressive functional limitation despite optimal medical therapy.

References: ATS/ERS/JRS/ALAT Clinical Practice Guideline for IPF; Fleischner Society ILD Guidelines.