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Lung Nodule (Fleischner 2017)

Follow-up recommendation for an incidentally detected pulmonary nodule, from the Fleischner Society 2017 guidelines (MacMahon et al., Radiology 2017).

Applies to incidentally detected nodules in patients ≥35 years. Does NOT apply to lung-cancer screening, immunosuppressed patients, or patients with a known primary cancer. Nodule size is the average of long and short axes, rounded to the nearest mm. Recommendations assume no suspicious morphology unless captured by the risk selection.

Encodes the Fleischner Society 2017 management tables for incidental solid and subsolid pulmonary nodules. Recommendations, not standard of care: deviate as the imaging and patient warrant.

Risk factors & source

Estimating risk (low vs high)

High-risk features include older age, heavy smoking, other known risk factors, irregular or spiculated margins, and upper-lobe location. Low risk applies to minimal or absent smoking history and other risk factors. Clinical judgment and, where appropriate, a validated risk calculator should guide the low- vs high-risk choice.

Measurement & definitions

Measure nodules as the average of long- and short-axis diameters on the same image, rounded to the nearest mm. Volumetric thresholds in the source: <100 mm³ (<6 mm), 100–250 mm³ (6–8 mm), >250 mm³ (>8 mm). For part-solid nodules, the solid-component size drives suspicion: a persistent solid component ≥6 mm is highly suspicious.

MacMahon H, Naidich DP, Goo JM, et al. Guidelines for Management of Incidental Pulmonary Nodules Detected on CT Images: From the Fleischner Society 2017. Radiology 2017;284:228–243. Tables: Solid (A) and Subsolid (B) nodules.