| | Cancer | Lung Cancer
Lung Nodules: Evaluation, Risk Stratification, and Follow-Up
A lung nodule (pulmonary nodule) is a focal opacity ≤3 cm surrounded by lung parenchyma. >3 cm is a mass. Nodules are common incidental findings on CT (up to 50% of adults).
Morphologic Classification
- Solid: Uniform soft-tissue attenuation; obliterates vessels.
- Part-solid: Solid + ground-glass components; higher malignancy risk.
- Ground-glass (GGN): Hazy opacity preserving vessels; pure GGN vs. part-solid.
Risk Stratification (Fleischner Society 2017 Guidelines — Simplified)
| Nodule Type | Size | Low Risk (No Hx) | High Risk (Smoking, FHx, etc.) |
|---|---|---|---|
| Solid | <6 mm | No routine follow-up | Optional CT at 12 mo |
| Solid | 6–8 mm | CT at 6–12 mo, then 18–24 mo | CT at 6–12 mo, then 18–24 mo |
| Solid | >8 mm | CT at 3 mo, PET/CT, or biopsy | CT at 3 mo, PET/CT, or biopsy |
| Part-solid | <6 mm | No routine follow-up | CT at 12 mo |
| Part-solid | ≥6 mm | CT at 3–6 mo; if persistent, PET/biopsy | CT at 3–6 mo; if persistent, PET/biopsy |
| Pure GGN | <6 mm | No routine follow-up | CT at 12 mo |
| Pure GGN | ≥6 mm | CT at 6–12 mo, then q2y ×5 yrs | CT at 6–12 mo, then q2y ×5 yrs |