What is the approach to managing pulmonary nodules according to the Fleischer guidelines?

Fleischner Society Guidelines for Pulmonary Nodule Management

The Fleischner Society 2017 guidelines provide a risk-stratified, size-based approach to managing incidentally detected pulmonary nodules, with recommendations varying by nodule type (solid vs. subsolid), size, multiplicity, and patient risk factors. 1

Technical Requirements for Nodule Evaluation

• All chest CT scans must be reconstructed with thin sections (≤1.5 mm, typically 1.0 mm) to enable accurate nodule characterization and measurement. 1
• Coronal and sagittal reconstructions should be routinely archived to facilitate distinction between nodules and scars. 1
• Thick sections increase volume averaging and preclude accurate assessment of part-solid morphology, fat, or calcium content. 1

Solid Nodules: Management Algorithm

Low-Risk Patients (No significant smoking history or other risk factors)

Nodules <4 mm:

• No routine follow-up required. 1
• Patient should be informed about potential benefits and harms of this approach. 1
• Malignancy risk is <1%. 1, 2

Nodules 4-6 mm:

• Optional CT at 12 months. 1
• No additional follow-up needed if unchanged. 1

Nodules >6-8 mm:

• CT at 6-12 months, then at 18-24 months if unchanged. 1

Nodules >8 mm:

• CT at 3 months, PET/CT, or tissue sampling should be considered. 1

High-Risk Patients (Smokers, age ≥65, family history, prior malignancy)

Nodules <4 mm:

• Optional CT at 12 months. 1

Nodules 4-6 mm:

• CT at 3-6 months, then at 18-24 months. 1

Nodules >6-8 mm:

• CT at 3-6 months, then at 18-24 months. 1
• Certain high-risk patients with suspicious morphology or upper lobe location may warrant 12-month follow-up. 1

Nodules >8 mm:

• CT at 3 months, PET/CT, or tissue sampling. 1

Subsolid Nodules: Management Algorithm

Pure Ground-Glass Nodules

<6 mm (<100 mm³):

• No routine follow-up. 1
• Multiple ground-glass nodules <6 mm are usually benign, but consider follow-up at 2 and 4 years in selected high-risk patients. 1

≥6 mm (>100 mm³):

• CT at 6-12 months to confirm persistence. 1
• If persistent, annual CT for 5 years. 1
• Ground-glass nodules >10 mm that persist beyond 3 months have 10-50% malignancy probability. 2

Part-Solid Nodules

<6 mm:

• No routine follow-up. 1
• Part-solid nodules cannot be reliably defined as such until ≥6 mm. 1

≥6 mm:

• CT at 3-6 months to confirm persistence. 1
• If unchanged and solid component remains <6 mm, perform annual CT for 5 years. 1
• Persistent part-solid nodules with solid components ≥6 mm should be considered highly suspicious and resection should be considered. 1

Multiple Nodules

Low-risk patients:

• No routine follow-up for multiple nodules when all are small. 1
• CT at 3-6 months, then consider CT at 18-24 months for larger nodules. 1

High-risk patients:

• Optional CT at 12 months for small nodules. 1
• CT at 3-6 months, then at 18-24 months for larger nodules. 1

Use the most suspicious nodule as guide to management; follow-up intervals may vary according to size and risk. 1

Critical Exclusions and Caveats

These guidelines do NOT apply to:

• Lung cancer screening programs. 1
• Immunosuppressed patients. 1
• Patients with known primary cancer. 1
• Patients <40 years of age (per some interpretations). 1

Benign Nodule Characteristics (No Follow-up Required)

The following nodule characteristics indicate benignity and require no follow-up: 1, 3

• Smoothly marginated nodules with internal fat and calcification (hamartoma). 1
• Central, laminar, diffuse, or "popcorn" calcification patterns (healed granulomas). 1, 3
• Triangular subpleural nodules with linear extension to pleural surface (intrapulmonary lymph nodes). 3
• Stability for at least 2 years. 3

Common Pitfalls to Avoid

• Do not confuse ground-glass opacities with emphysema—they require distinct evaluation and follow-up. 4
• Do not confuse pulmonary nodules with emphysema—they have different follow-up criteria. 4
• Thick-section CT imaging precludes accurate characterization; obtain thin sections if initial scan used thick slices. 1
• In patients with multiple nodules, five or more nodules likely represent prior granulomatous infection rather than malignancy. 3
• Adherence to guidelines can be suboptimal (reported as low as 34% in some studies); institutional protocols and decision support tools improve compliance. 1

Risk Factors to Consider

High-risk features include: 1, 3

• Smoking history
• Age ≥65 years
• Family history of lung cancer
• Prior malignancy
• Upper lobe location
• Spiculated or irregular margins
• Emphysema (independent risk factor for lung cancer with 25 cases per 1000 patients vs. 7.5 per 1000 without). 4