Guidelines for management of incidental pulmonary nodules on CT
Average of long and short axis on axial images
For part-solid nodules only
Check all that apply. Any factor = HIGH risk patient.
The Fleischner Society guidelines provide evidence-based recommendations for managing incidental pulmonary nodules detected on CT imaging. These guidelines help reduce unnecessary follow-up imaging and invasive procedures while ensuring appropriate surveillance of potentially malignant nodules.
These guidelines apply to incidental pulmonary nodules in adults aged 35 years or older. They do NOT apply to:
Completely soft tissue attenuation, obscuring the underlying lung parenchyma. Risk stratification is based on size and patient risk factors.
Hazy increased attenuation that does not obscure underlying bronchial or vascular structures. Pure GGNs have lower malignancy risk but may represent adenocarcinoma spectrum lesions (atypical adenomatous hyperplasia, adenocarcinoma in situ).
Mixed ground-glass and solid components. The solid component size is the key prognostic factor, correlating with invasive adenocarcinoma. Part-solid nodules have the highest malignancy risk among all nodule types.
Patients are classified as HIGH RISK if they have ANY of:
| Nodule Type | Threshold | Significance |
|---|---|---|
| Solid | 6 mm | Below this, minimal follow-up in low-risk patients |
| Solid | 8 mm | Above this, consider PET/CT or biopsy |
| Subsolid (GGN/Part-solid) | 6 mm | Below this, no routine follow-up |
| Part-solid (solid component) | 6 mm | Above this, consider PET/biopsy/resection |
Nodule size should be measured as the average of long and short axis diameters on axial images. For part-solid nodules, measure both total size and solid component size. Measurements should be made on lung windows. Volume measurement, when available, may provide more accurate growth assessment.