Fleischner Guidelines for Managing Pulmonary Nodules
The Fleischner Society guidelines provide a structured, evidence-based approach for managing incidental pulmonary nodules based on nodule size, morphology, and patient risk factors, with different follow-up protocols for solid and subsolid nodules. 1
Classification of Nodules
- Solid nodules: Well-defined opacities that completely obscure underlying vessels
- Subsolid nodules: Include:
- Ground-glass nodules (through which underlying structures can be seen)
- Partially solid nodules (combination of solid and ground-glass components) 1
Size-Based Management Recommendations
Solid Nodules
| Nodule Size | Low-Risk Patient | High-Risk Patient |
|---|---|---|
| <6 mm (<100 mm³) | No routine follow-up | Optional CT at 12 months |
| 6-8 mm (100-250 mm³) | CT at 6-12 months, consider additional CT at 18-24 months if stable | CT at 6-12 months, consider additional CT at 18-24 months if stable |
| >8 mm (>250 mm³) | CT at 3 months, PET/CT, or biopsy | CT at 3 months, PET/CT, or biopsy |
Subsolid Nodules
| Nodule Type | Management |
|---|---|
| ≥6 mm with solid component <6 mm | CT at 3-6 months, then annually for 5 years |
| ≥6 mm with solid component ≥6 mm | CT at 3-6 months, then consider PET/CT, biopsy, or resection if persistent |
Risk Stratification
High-risk factors include:
- Age >60 years
- History of smoking
- Family history of lung cancer
- Previous history of malignancy
- Exposure to carcinogens
- Underlying lung disease
- Irregular/spiculated nodule morphology 1
Technical Imaging Recommendations
- CT scans should be reconstructed with thin sections (≤1.5 mm, typically 1.0 mm)
- Coronal and sagittal reconstructions are strongly recommended
- Nodule measurements should be performed using electronic calipers or semi-automatic methods
- Size should be calculated as the average of long and short axes rounded to the nearest millimeter 1, 2
Special Considerations
- Nodules with benign characteristics (diffuse, central, laminated or popcorn calcification, macroscopic fat, or typical perifissural location) do not require follow-up 1
- Multiple nodules should be managed based on the most suspicious nodule
- For small nodules (<6 mm) on incomplete thoracic CT scans, additional investigation is generally not required 1
Exclusions
The Fleischner guidelines do not apply to:
- Patients under 35 years
- Immunocompromised patients
- Patients with known primary cancer
- Lung cancer screening programs 1
Clinical Impact
Implementation of the 2017 updated Fleischner guidelines has been shown to:
- Reduce unnecessary follow-up CT examinations by up to 64.5% compared to previous guidelines 3
- Maintain diagnostic accuracy for detecting malignant nodules 4
- Decrease radiation exposure for patients 4
The guidelines aim to balance the need to identify potentially malignant nodules while reducing unnecessary follow-up imaging, healthcare costs, and radiation exposure.