Incidental pulmonary nodule — CT (Fleischner)

1.Size

Mean of long- and short-axis on the same transverse image, in mm, on lung windows. Report the average; volume where available.

Pitfall: Rounding down across the 6 mm or 8 mm threshold changes the recommendation.

2.Attenuation

Solid, pure ground-glass, or part-solid. For part-solid nodules, measure the solid component separately.

3.Morphology

Margins (smooth, lobulated, spiculated). A smooth perifissural nodule with triangular/lentiform shape is typically a benign intrapulmonary node.

4.Location

Lobe and segment, to allow accurate comparison on follow-up.

5.Number

Single or multiple. With multiple nodules, follow-up is guided by the most suspicious one.

6.Comparison with priors

Assess stability. Solid nodules stable ≥2 years and subsolid nodules stable ≥5 years are generally benign.

7.Risk factors

Smoking history, age, emphysema/fibrosis, upper-lobe location, and family history determine the low- vs high-risk pathway.