What is the management approach for an adult patient, potentially with a history of smoking, found to have a groundglass (ground glass) nodule on computed tomography (CT) scan?

Management of Ground-Glass Nodules

Ground-glass nodules require a size-based surveillance approach with initial follow-up at 3 months to exclude infectious etiology, followed by extended surveillance for persistent nodules, as these lesions—while often representing early adenocarcinoma—demonstrate indolent behavior that allows for conservative management prioritizing quality of life over aggressive intervention. 1

Initial Assessment and Risk Stratification

Size-Based Triage

• Do not follow ground-glass nodules <5 mm in maximum diameter, as these have negligible malignancy risk and surveillance provides no mortality benefit 1, 2
• Ground-glass nodules ≥5 mm require initial thin-section CT at 3 months to distinguish infectious/inflammatory lesions (which resolve) from persistent nodules requiring long-term surveillance 1, 3
• All CT imaging must use thin sections ≤1.5 mm (typically 1.0 mm) with coronal and sagittal reconstructions to accurately characterize ground-glass attenuation and detect solid components 1

Critical Distinction: Pure vs Part-Solid

• Pure ground-glass nodules (no solid component) have lower malignancy risk and slower growth rates, typically representing adenocarcinoma in situ or minimally invasive adenocarcinoma with 100% survival when treated 3, 4
• Part-solid nodules (containing any solid component) carry significantly higher malignancy risk and are the only predictor of nodule growth in follow-up studies 5, 6
• The presence of a solid component, vascular convergence sign, lobulation, spiculation, or pleural tags increases malignancy probability to >90% 6

Surveillance Protocol for Persistent Ground-Glass Nodules

For Pure Ground-Glass Nodules ≥5 mm

• Repeat CT at 3 months after baseline to confirm persistence and exclude infectious etiology 1, 3
• If resolved at 3 months, discharge from surveillance 3
• If persistent at 3 months, use the Brock risk prediction model to calculate malignancy risk 1
• For low-risk nodules (<10% malignancy probability): Continue surveillance at 1,2, and 4 years from baseline 1, 2
• Annual surveillance should extend for at least 3-5 years total, as ground-glass nodules demonstrate extremely slow growth patterns 1, 2

For Part-Solid Nodules

• Part-solid nodules ≤8 mm: CT surveillance at 3,12, and 24 months, followed by annual CT for 1-3 additional years 2
• Part-solid nodules >8 mm: Repeat CT at 3 months, then proceed to PET-CT, biopsy, or surgical resection for persistent nodules 2
• For nodules with risk of malignancy >10%: Discuss options of observation, CT-guided biopsy, or resection/non-surgical treatment, considering patient age, comorbidities, and surgical risk 1

Indicators for Escalation to Intervention

Growth Criteria Requiring Action

• Pure ground-glass nodules that enlarge ≥2 mm in maximum diameter warrant consideration of resection or continued close observation with repeat CT in 6 months maximum 1
• Part-solid nodules showing enlargement of the solid component, or pure ground-glass nodules developing a new solid component, favor resection over observation 1
• Change in mass (volumetric assessment) provides more accurate growth detection than diameter measurements when available 1
• Development of concerning morphologic features (lobulation, spiculation, vascular convergence) during surveillance increases malignancy probability and warrants escalation 6

High-Risk Features Requiring Shorter Surveillance Intervals

• Female sex carries higher malignancy risk specifically for ground-glass nodules (not solid nodules) 1
• Upper lobe location, larger size, and presence of emphysema or pulmonary fibrosis increase malignancy risk 1
• Multiple ground-glass nodules suggest multifocal adenocarcinoma with ground-glass features, which paradoxically carries better prognosis than single lesions despite higher recurrence rates 1

Technical Considerations and Pitfalls

Biopsy Limitations

• Transthoracic needle biopsy has important limitations for ground-glass lesions due to inadequate sampling and false-negative results 1
• Ground-glass nodules may have lower diagnostic yield with standard bronchoscopic techniques 2
• Non-diagnostic biopsy results do not exclude malignancy and may require repeat sampling or surgical resection 2

Radiation Dose Optimization

• Use low-dose CT technique for surveillance imaging with volumetric CT dose index (CTDIvol) ≤3 mGy in standard-size patients 1
• Limit follow-up CT to the nodule of record rather than full chest CT when appropriate to minimize cumulative radiation exposure 2

Common Management Errors to Avoid

• Do not skip the 3-month follow-up based on clinical judgment alone—this critical timepoint distinguishes infectious from malignant etiology and prevents unnecessary prolonged surveillance 3
• Do not proceed directly to biopsy or resection for persistent ground-glass nodules without documented growth, as these lesions are typically indolent and surveillance-first approach preserves quality of life 5, 4
• Do not use thick-section CT (>3 mm) for surveillance, as volume averaging obscures solid components and prevents accurate characterization 1, 2
• Always obtain prior imaging if available—nodules stable for ≥2 years require no further workup regardless of size 2

Special Clinical Scenarios

Multiple Ground-Glass Nodules

• Multiple pure ground-glass or part-solid nodules represent multifocal lung adenocarcinoma with ground-glass features, classified by the T category of the lesion with highest T, with number of lesions indicated in parentheses 1
• These patients have better prognosis with less nodal involvement despite higher risk of developing subsequent lesions 1
• Base surveillance frequency on the largest/highest-risk nodule rather than total nodule count 2

Pneumonic-Type Presentation

• Ground-glass opacities presenting as patchy consolidation typically represent invasive mucinous adenocarcinoma with better prognosis than non-mucinous types 1
• Staging accounts for extent of disease: T3 if whole lobe involved, T4 if multiple ipsilateral lobes, M1a if bilateral 1