What is the management approach for increased interstitial lung markings?

Management of Increased Interstitial Lung Markings

For patients with increased interstitial lung markings (interstitial lung abnormalities), obtain high-resolution CT chest to confirm findings, perform baseline pulmonary function testing (FVC, TLC, DLCO), evaluate for underlying causes including connective tissue disease and exposures, and establish serial monitoring with repeat CT in 2-3 years (or 12 months if high-risk features present). 1

Initial Diagnostic Confirmation and Classification

• Confirm the radiologic pattern with high-resolution CT (HRCT) if not already performed, as HRCT has 91% sensitivity and 71% specificity for diagnosing ILD subtypes 2
• Verify that findings occupy >5% of a nondependent lung zone to meet criteria for interstitial lung abnormality 3
• Classify the radiologic pattern as non-subpleural, subpleural nonfibrotic, or subpleural fibrotic, as this determines risk stratification 3

Baseline Clinical Assessment

Symptom Evaluation

• Assess for dyspnea on exertion and non-productive cough that may be attributable to the lung findings 1
• Note that 90% of HRCT-confirmed ILD patients may not report dyspnea or cough, so absence of symptoms does not exclude significant disease 4
• Any amount of dyspnea and/or cough attributed to ILD by the clinician upgrades the diagnosis from ILA to ILD 1

Pulmonary Function Testing

• Obtain baseline spirometry with FVC, total lung capacity (TLC), and diffusion capacity (DLCO) 1
• Any value below the lower limit of normal that you attribute to ILD upgrades the diagnosis from ILA to ILD 1
• A 5% FVC decline over 12 months is associated with approximately 2-fold increased mortality 4, 2

Physical Examination

• Auscultate for fine inspiratory "velcro" crackles, which have moderate sensitivity for early ILD identification 4

Etiologic Evaluation

Screen for Connective Tissue Disease

• Order rheumatoid factor, anti-CCP antibodies, ANA, anti-Scl-70, anti-Jo-1, and other myositis-specific antibodies to differentiate SARD-associated ILD from idiopathic disease 5
• CTD-associated ILD represents 20% of all ILD cases, with rheumatoid arthritis and systemic sclerosis being most common 4
• Consider rheumatology referral if CTD markers are positive or clinical features suggest autoimmune disease 1

Exposure History

• Obtain detailed environmental and occupational exposure history including organic antigens, silica, asbestos, and drug toxicity 5
• Use systematic standardized questionnaires for hypersensitivity pneumonitis evaluation, though causative antigens are often not identified 6

Family History

• Document family history of pulmonary fibrosis, as this is a high-risk feature for progression 1

Risk Stratification for Progression

High-Risk Features Requiring Closer Monitoring 1

• Definite fibrosis on CT (honeycombing, traction bronchiectasis, or architectural distortion)
• Subpleural fibrotic or subpleural nonfibrotic subtypes
• Greater extent of abnormalities involving multiple lung zones
• Abnormal or borderline FVC, TLC, or DLCO
• Family history of pulmonary fibrosis
• Older age and smoking history

Testing NOT Recommended

• Do not perform lung biopsy for histopathological analysis at baseline unless the patient meets criteria for ILD per existing guidelines 1
• Do not test for MUC5B promoter variant (rs35705950) as it does not contribute unique and clinically actionable information 1
• Do not measure telomere length unless family history or clinical features suggest telomeropathy 1

Longitudinal Monitoring Strategy

Standard Follow-up

• Obtain repeat chest CT in 2-3 years for patients without high-risk features 1
• Consider earlier follow-up at 12 months if high-risk features are present 1

Proactive vs Reactive Monitoring

• Use proactive serial monitoring (scheduled regular intervals) if high-risk features for progression are present 3
• Use reactive monitoring (symptom-driven) if no high-risk features are present 3

Risk Reduction Interventions

• Counsel on smoking cessation including cigarettes, e-cigarettes, and cannabis 1
• Implement exposure remediation for identified environmental or occupational triggers 1
• Ensure age-appropriate vaccinations 1

Criteria for Upgrading from ILA to ILD

An ILA should be reclassified as ILD if ANY of the following are present: 1

Clinical Domain

• Any dyspnea and/or cough attributed to ILD by the clinician

Physiologic Domain

• Any abnormality in FVC, TLC, or DLCO below the lower limit of normal attributed to ILD
• Meets criteria for progressive pulmonary fibrosis

Imaging Domain

• Fibrotic abnormalities (honeycombing and/or reticulation with traction bronchiectasis) involving >5% of total lung volume 1
• Documented radiologic progression beyond initial findings 1

Treatment Considerations When ILD is Diagnosed

For CTD-Associated ILD

• Initiate mycophenolate mofetil as first-line immunosuppressive therapy across all SARD-ILD subtypes regardless of fibrosis pattern 5, 4
• Consider rituximab or tocilizumab as alternative immunomodulatory options 5, 4

For Idiopathic Pulmonary Fibrosis Pattern

• Initiate antifibrotic therapy with nintedanib or pirfenidone if definite UIP pattern is present, as these agents slow annual FVC decline by 44-57% 5, 2
• Do not use immunosuppressive therapy for IPF, as it is not effective and may be harmful 5

For Progressive Pulmonary Fibrosis

• Monitor for PPF phenotype defined as ≥10% decline in FVC, worsening respiratory symptoms, and/or radiographic progression within the past year despite treatment 5
• Consider adding nintedanib to ongoing immunosuppressive therapy if PPF develops in SARD-ILD 5

Common Pitfalls to Avoid

• Do not dismiss normal pulmonary function tests in sedentary patients, as symptoms may be absent and physiology can represent significant decline from supranormal baseline values 1
• Do not assume isolated reticulation without traction bronchiectasis represents ILD unless progression is documented 1
• Do not delay multidisciplinary discussion when findings are subtle or mixed patterns are present 3
• Do not overlook pulmonary arterial hypertension screening, as up to 85% of individuals with end-stage fibrotic ILD develop this complication 2