What is the diagnosis and treatment for a patient with coarse reticular markings on the chest, more pronounced on the right side, suggestive of fibrotic disease?

Diagnosis and Management of Coarse Reticular Markings Suggesting Fibrotic Disease

Coarse reticular markings with asymmetric distribution (right > left) most likely represent idiopathic pulmonary fibrosis (IPF) with a usual interstitial pneumonia (UIP) pattern, though hypersensitivity pneumonitis (HP) and other fibrotic interstitial lung diseases must be excluded through systematic evaluation. 1

Diagnostic Approach

Initial Imaging Characterization

Obtain high-resolution CT (HRCT) scanning immediately, as this is the cornerstone of diagnosis and can establish IPF without surgical lung biopsy in appropriate cases. 1

The HRCT must be evaluated for specific patterns:

• UIP pattern features: Reticular opacities with subpleural and basal predominance, traction bronchiectasis/bronchiolectasis, and honeycombing (clustered cystic airspaces 3-10mm with thickened walls). 1
• Probable UIP pattern: Reticular pattern with peripheral traction bronchiectasis but without definite honeycombing. 1
• Distribution asymmetry: While IPF is typically bilateral, asymmetric involvement can occur and does not exclude the diagnosis. 1

Critical Differential Diagnosis Considerations

Exclude hypersensitivity pneumonitis (HP) systematically, as this is the most important alternative diagnosis that changes management completely. 1

Look for HP-specific features on HRCT:

• Three-density sign (mosaic attenuation with areas of ground-glass, normal lung, and decreased attenuation in three or more lobes) has 93-96% specificity for fibrotic HP. 1
• Profuse centrilobular ground-glass nodules affecting all lung zones. 1
• Mosaic attenuation and air-trapping more extensive than reticulation. 1
• Mid-lung or upper lobe predominance (less common in IPF). 1

Obtain detailed exposure history focusing on:

• Bird or down feather exposure (including bedding). 1
• Mold exposure (water damage, humidifiers). 1
• Occupational exposures (farming, livestock, industrial). 1, 2

Mandatory Exclusion Criteria

Before diagnosing IPF, systematically exclude:

• Connective tissue diseases: Check ANA, rheumatoid factor, anti-CCP antibodies, myositis panel. High titers (>1:160) suggest CTD-related ILD rather than IPF. 1
• Drug toxicity: Review medication history for known fibrogenic drugs (amiodarone, methotrexate, nitrofurantoin, chemotherapy agents). 1
• Occupational/environmental exposures: Asbestos (look for pleural plaques on CT), silica, metal dusts. 1, 2

Pulmonary Function Testing

Obtain spirometry with DLCO showing:

• Restrictive pattern (reduced FVC, often increased FEV1/FVC ratio). 1
• Impaired gas exchange (decreased DLCO, increased A-a gradient). 1
• These findings support but do not confirm IPF. 1

Role of Surgical Lung Biopsy

Surgical lung biopsy (SLB) is indicated when:

• HRCT shows "indeterminate for UIP" pattern (fibrosis without specific features). 1
• HRCT suggests alternative diagnosis but clinical suspicion for IPF remains high. 1
• Patient is young (<50 years) or has atypical features. 1

SLB should NOT be performed when:

• HRCT shows definite UIP pattern in appropriate clinical context. 1
• Patient has significant comorbidities, advanced age, or severe disease making surgery high-risk. 1
• Patient declines procedure. 1

Multidisciplinary Discussion

Refer to or conduct multidisciplinary discussion (MDD) involving pulmonologist, radiologist, and pathologist before finalizing diagnosis, as MDD changes diagnosis in a significant proportion of cases. 1

Treatment Recommendations

For Confirmed IPF (UIP Pattern)

Initiate antifibrotic therapy with pirfenidone or nintedanib immediately upon diagnosis. 3

Pirfenidone dosing:

• Target dose: 2,403 mg/day (801 mg three times daily with food). 3
• Demonstrated reduction in FVC decline (mean treatment difference 193 mL at 52 weeks). 3
• Reduces proportion of patients with ≥10% FVC decline. 3

Key management principles:

• Antifibrotics slow but do not reverse fibrosis; early initiation is critical. 3
• Monitor FVC every 3-6 months to assess disease progression. 3
• Refer for lung transplant evaluation if FVC <50% or DLCO <35%. 3
• Supplemental oxygen for resting or exertional hypoxemia. 2

For Fibrotic Hypersensitivity Pneumonitis

If HP is diagnosed, management differs fundamentally:

• Antigen avoidance is primary therapy (remove birds, replace bedding, remediate mold). 1
• Consider corticosteroids for inflammatory component. 1
• Antifibrotics may be considered for progressive fibrotic HP. 1, 4

For Indeterminate Cases

When diagnosis remains uncertain after HRCT and clinical evaluation:

• Consider empiric antifibrotic therapy if progressive fibrotic phenotype is present, as multiple fibrotic ILDs now have antifibrotic indications. 4
• Close monitoring with serial PFTs every 3-4 months. 4
• Reassess with repeat HRCT in 6-12 months if stable. 4

Critical Pitfalls to Avoid

• Do not diagnose IPF without excluding HP, as missing HP leads to continued antigen exposure and preventable progression. 1
• Do not rely on chest radiograph alone; HRCT is mandatory as chest X-ray diagnosis of IPF is only 48-87% accurate. 1
• Do not delay antifibrotic therapy once IPF is confirmed; median survival is 2-5 years and treatment only slows progression. 3, 2
• Do not assume bilateral symmetry is required; asymmetric distribution can occur in IPF. 1
• Do not perform SLB when HRCT shows definite UIP pattern in appropriate clinical context, as this unnecessarily exposes patients to surgical risk. 1