What is the management approach for patients presenting with reticulation and honeycombing on lung imaging?

Management of Reticulation and Honeycombing on Lung Imaging

Patients with reticulation and honeycombing on lung imaging should be managed through a multidisciplinary approach with pulmonologists, radiologists, and pathologists experienced in interstitial lung diseases, with high-resolution CT (HRCT) findings being the cornerstone of diagnosis and management decisions. 1

Diagnostic Approach

HRCT Pattern Assessment

• Definite UIP pattern: Characterized by:

  • Subpleural and basal predominance
  • Reticular abnormality
  • Honeycombing with or without traction bronchiectasis
  • Absence of features inconsistent with UIP 1

• Possible UIP pattern: Characterized by:

  • Subpleural and basal predominance
  • Reticular abnormality
  • Absence of honeycombing
  • Absence of features inconsistent with UIP 1

• Inconsistent with UIP pattern: Any of these features:

  • Upper or mid-lung predominance
  • Extensive ground-glass abnormality
  • Profuse micronodules
  • Consolidation in bronchopulmonary segments/lobes 1

Diagnostic Algorithm

1. When honeycombing is present on HRCT with typical distribution (subpleural, basal):

   • Diagnosis of IPF can be established without surgical lung biopsy if other causes of ILD have been excluded 1

2. When reticulation is present without honeycombing:

   • Consider surgical lung biopsy (SLB) or transbronchial lung cryobiopsy (TBLC)
   • TBLC is now considered an acceptable alternative to SLB 1
   • Decision for biopsy should account for patient age, comorbidities, disease severity, and progression 1

3. When biopsy cannot be performed (due to contraindications or patient refusal):

   • Rely on multidisciplinary discussion
   • Consider bronchoalveolar lavage (BAL) to rule out alternative diagnoses 1

Management Considerations

Prognostic Assessment

• Honeycombing is a significant prognostic marker:

  • Associated with increased mortality across diverse ILDs (HR 1.62; 95% CI, 1.29-2.02) 2
  • Identifies a progressive fibrotic phenotype with high mortality 2
  • The extent of honeycombing correlates with disease progression risk 3

• Reticulation without honeycombing:

  • High extent of reticulation is associated with disease progression (OR 3.11,95% CI 1.21-7.98) 4
  • Approximately 53% of patients with reticulation show disease progression within 24 months 4
  • Reticulation is an independent predictor of radiological progression (OR 1.9; 95% CI, 1.2-3.0) 5

Treatment Approach

1. For IPF with honeycombing:

   • Antifibrotic therapy should be considered
   • Regular monitoring of pulmonary function (FVC and DLCO)
   • Oxygen therapy as needed for hypoxemia

2. For non-IPF ILDs with honeycombing:

   • Consider treatment similar to IPF due to similar mortality patterns 2
   • Evaluate for underlying causes (connective tissue disease, hypersensitivity pneumonitis)

3. For reticulation without honeycombing:

   • Close monitoring is essential as progression risk is high 4, 5
   • Consider early intervention, particularly with extensive reticulation

Monitoring Protocol

• Pulmonary function tests (FVC and DLCO) every 3-6 months
• 6-minute walk test to assess exercise capacity and oxygen desaturation
• Follow-up HRCT at 6-12 month intervals to assess for:
  • Development of honeycombing
  • Progression of reticulation
  • Increase in traction bronchiectasis

Risk Stratification: The HTM Score

The Honeycombing, Traction bronchiectasis, and Monocyte (HTM) score can be used to predict 1-year progression risk 3:

• Monocyte count ≥0.65 G/L: 1 point
• Combined honeycombing or traction bronchiectasis score:
  • 0 lung fields: 0 points
  • 1-4 lung fields: 1 point
  • 5-6 lung fields: 2 points

Progression risk by score:

• Score 0: 0-20% risk
• Score 1: 23-25% risk
• Score 2: 47-54% risk
• Score 3: 63-89% risk

Important Caveats

• Not all patients with reticulation will develop honeycombing - some may progress chronically without developing honeycombing 6
• The appearance of honeycombing during follow-up might not necessarily worsen prognosis in all cases 6
• Differentiate true honeycombing (clustered cystic spaces 3-10mm with thick walls) from other cystic lung diseases like subpleural blebs (typically <1-2cm in apical regions) 7
• Never smoking has been associated with disease progression in some studies (OR 3.11, CI 1.12-8.63), contrary to what might be expected 4