What is the recommended management for smoking‑related interstitial lung disease, specifically respiratory bronchiolitis‑associated interstitial lung disease (RB‑ILD) or desquamative interstitial pneumonia (DIP) in current or former smokers?

Management of Smoking-Related Interstitial Lung Disease

Smoking cessation is the cornerstone of treatment for RB-ILD and DIP, with resolution of symptoms in up to 90% of cases and improvement of cough in 94-100% of patients within the first year. 1

Primary Treatment Strategy

Immediate smoking cessation is mandatory and represents the single most effective intervention for both RB-ILD and DIP. 1 This should be achieved through:

• Combination pharmacotherapy: Use nicotine replacement therapy (patch plus short-acting form) OR varenicline as first-line agents 1
• Behavioral counseling: At least 4 sessions during each 12-week course of pharmacotherapy 1
• Environmental modification: Complete elimination of secondhand smoke exposure and avoidance of occupational/environmental pollutants 1

Corticosteroid Therapy

Corticosteroids provide modest clinical benefit but rarely achieve complete disease resolution. 2 Consider corticosteroid therapy in patients with:

• Persistent symptoms despite smoking cessation 2, 3
• Significant functional impairment 4
• Progressive disease on imaging or pulmonary function testing 2

Important caveat: Corticosteroids are associated with partial response rather than cure, and persistent abnormalities on pulmonary function testing and imaging commonly persist despite treatment. 2

Diagnostic Approach

RB-ILD can increasingly be diagnosed without surgical lung biopsy in smokers presenting with characteristic HRCT findings (ground-glass opacities and centrilobular nodules) when bronchoalveolar lavage demonstrates smokers' macrophages and absence of lymphocytosis. 5

• Transbronchial biopsy is typically nondiagnostic and should not delay treatment 2
• Surgical lung biopsy remains the gold standard when diagnosis is uncertain 2

Disease Course and Prognosis

The clinical course is heterogeneous and unpredictable:

• RB-ILD: Generally has a substantially better prognosis than idiopathic pulmonary fibrosis 1, but a significant minority progress despite smoking cessation 5, 1
• DIP: 10-year survival is approximately 70%, with treatment resistance in a significant minority 5, 1
• Progressive disease with death can occur, particularly in DIP patients who continue smoking 2

Monitoring Strategy

Follow-up imaging at 3-6 month intervals is essential to monitor disease progression, especially if initial evaluation is non-diagnostic or response to treatment is uncertain. 1

• Serial pulmonary function testing to assess for functional decline 2, 4
• HRCT to evaluate radiologic progression or improvement 1

Critical Pitfalls to Avoid

• Do not assume smoking cessation alone will resolve disease: A significant minority progress despite cessation 5, 4
• Do not withhold corticosteroids in symptomatic patients: While response is often partial, some patients derive meaningful benefit 2, 3
• Do not confuse with other ILDs: Distinguish from hypersensitivity pneumonitis (which shows lymphocytosis on BAL) and NSIP (which shows subpleural sparing) 5, 1
• Continued smoking portends worse outcomes: Progressive disease and death are more likely in patients who continue smoking 2