Management and follow-up calculator for incidental solid and subsolid pulmonary nodules using Fleischner and NCCN guidelines.
Text summary of the rules this calculator applies, generated from the same definitions the calculation uses.
The Fleischner 2017 guidelines apply to incidental pulmonary nodules (found outside a screening program) in adults ≥ 35 years, excluding immunosuppressed patients or those with known cancer. The minimum size threshold for recommending follow-up is based on an estimated cancer risk on the order of ≥ 1%.
| Variable | Definition | Possible values | Unit |
|---|---|---|---|
| Does it meet ALL of these criteria? | Density: solid, non-calcified, no fat; Borders: smooth, well-defined, no arterial attachment; Size: ≤ 12 mm maximum diameter; No red flags for malignancy (e.g., spiculation, pleural/fissural retraction, or not being influenced by neighboring structures) | Yes · No | Yes / No |
| Is it a fissural nodule? | Location: major, minor, or accessory fissure; Shape: lentiform or polygonal in ≥ 2 orthogonal views | Yes · No | Yes / No |
| Is it a juxtapleural nodule? | Location: ≤ 15 mm of the visceral pleura AND in the lower lobe, middle lobe, or lingula; Shape: oval (not spherical) in 3 orthogonal views, OR lentiform/polygonal in ≥ 2 views | Yes · No | Yes / No |
| Reference framework for the recommendation | — | Fleischner 2017 · NCCN (incidental nodule algorithm) | Categorical |
| Nodule type | Subsolid nodules (ground-glass or part-solid) require longer follow-up than solid nodules because in situ/minimally invasive adenocarcinoma can grow slowly. For multiple subsolid nodules, both frameworks agree on management guided by the most suspicious nodule. | Solid · Subsolid - part-solid · Subsolid - pure ground-glass | Categorical |
| Number of nodules | — | Single · Multiple | Categorical |
| Patient risk (solid nodules only) | Size is measured as the average of the long- and short-axis diameters on thin-section CT (≤ 1.5 mm). "High risk" includes significant smoking history or other lung cancer risk factors; the risk category is only defined for solid nodules, not for subsolid ones, in either framework. | Low risk · High risk (significant smoking history or other factors) | Categorical |
| Size (mm, average of diameters) | Size is measured as the average of the long- and short-axis diameters on thin-section CT (≤ 1.5 mm). "High risk" includes significant smoking history or other lung cancer risk factors; the risk category is only defined for solid nodules, not for subsolid ones, in either framework. | e.g. 7 | mm |
Before applying the size-based algorithm, assess whether the nodule meets the criteria for a perifissural nodule (PFN) — the CT representation of an intrapulmonary lymph node (IPLN), typically benign — which does not require further follow-up.
Step 1 (perifissural nodule / PFN) is based on the decision tree from Schreuder et al. (Radiology: Cardiothoracic Imaging 2020), which standardizes four prior PFN definitions from the literature. It applies only to solid, non-calcified, fat-free nodules of typical morphology; a nodule that does not meet Step 1 simply continues down the usual Fleischner/NCCN pathway — that alone does not imply higher suspicion of malignancy.
| Nodule type | Number of nodules | Patient risk (solid nodules only) | Size | Recommendation |
|---|---|---|---|---|
| Solid | Single | Low risk | < 6 mm | No routine follow-up needed. |
| Solid | Single | Low risk | 6–8 mm | CT at 6-12 months; then consider CT at 18-24 months. |
| Solid | Single | Low risk | > 8 mm | Consider CT at 3 months, PET/CT, or tissue sampling. |
| Solid | Single | High risk (significant smoking history or other factors) | < 6 mm | Optional CT at 12 months. Nodules < 6 mm do not require routine follow-up, but in high-risk patients with suspicious nodule morphology, upper-lobe location, or both, 12-month follow-up may be warranted. |
| Solid | Single | High risk (significant smoking history or other factors) | 6–8 mm | CT at 6-12 months, then CT at 18-24 months. |
| Solid | Single | High risk (significant smoking history or other factors) | > 8 mm | Consider CT at 3 months, PET/CT, or tissue sampling. |
| Solid | Multiple | Low risk | < 6 mm | No routine follow-up needed. |
| Solid | Multiple | Low risk | ≥ 6 mm | CT at 3-6 months; then consider CT at 18-24 months. |
| Solid | Multiple | High risk (significant smoking history or other factors) | < 6 mm | Optional CT at 12 months. Nodules < 6 mm do not require routine follow-up, but in high-risk patients with suspicious nodule morphology, upper-lobe location, or both, 12-month follow-up may be warranted. |
| Solid | Multiple | High risk (significant smoking history or other factors) | ≥ 6 mm | CT at 3-6 months, then CT at 18-24 months. |
| Subsolid - part-solid | Single | Not applicable | < 6 mm | No routine follow-up needed. |
| Subsolid - part-solid | Single | Not applicable | ≥ 6 mm | CT at 3-6 months to confirm persistence; if unchanged and the solid component remains < 6 mm, annual CT for a minimum of 5 years; if the solid component grows or is suspicious, consider PET/CT, biopsy, or resection. |
| Subsolid - part-solid | Multiple | Not applicable | < 6 mm | CT at 3-6 months; if stable, consider CT at 2 and 4 years (especially in high-risk patients). |
| Subsolid - part-solid | Multiple | Not applicable | ≥ 6 mm | CT at 3-6 months; subsequent management guided by the most suspicious nodule(s). |
| Subsolid - pure ground-glass | Single | Not applicable | < 6 mm | No routine follow-up needed. |
| Subsolid - pure ground-glass | Single | Not applicable | ≥ 6 mm | CT at 6-12 months to confirm persistence; if persistent, CT every 2 years until 5 years. |
| Subsolid - pure ground-glass | Multiple | Not applicable | < 6 mm | CT at 3-6 months; if stable, consider CT at 2 and 4 years (especially in high-risk patients). |
| Subsolid - pure ground-glass | Multiple | Not applicable | ≥ 6 mm | CT at 3-6 months; subsequent management guided by the most suspicious nodule(s). |
For single solid nodules, the > 8 mm threshold triggers a more active work-up (CT at 3 months, PET/CT, or biopsy); for multiple solid nodules, even above 8 mm, Fleischner keeps the more conservative CT at 3-6 months pathway (the dominant nodule is prioritized). Difference between frameworks: the NCCN incidental nodule table does not distinguish between single and multiple solid nodules (it uses the same size/risk-based management for both) — that count-based distinction is specific to Fleischner 2017.
| Nodule type | Number of nodules | Patient risk (solid nodules only) | Size | Recommendation |
|---|---|---|---|---|
| Solid | Any | Low risk | < 6 mm | No routine follow-up. |
| Solid | Any | Low risk | 6–8 mm | CT at 6-12 months; if stable, consider CT at 18-24 months. |
| Solid | Any | Low risk | > 8 mm | Consider CT at 3 months, PET/CT, or biopsy. |
| Solid | Any | High risk (significant smoking history or other factors) | < 6 mm | CT at 12 months (optional); if stable, no routine follow-up. |
| Solid | Any | High risk (significant smoking history or other factors) | 6–8 mm | CT at 6-12 months; if stable, repeat CT at 18-24 months. |
| Solid | Any | High risk (significant smoking history or other factors) | > 8 mm | Consider CT at 3 months, PET/CT, or biopsy. |
| Subsolid - part-solid | Single | Not applicable | < 6 mm | No routine follow-up. |
| Subsolid - part-solid | Single | Not applicable | ≥ 6 mm | CT at 3-6 months to confirm no growth/change in the solid component; then annual CT for 5 years. If solid component ≥ 6 mm, consider PET/CT or biopsy. |
| Subsolid - part-solid | Multiple | Not applicable | < 6 mm | CT at 3-6 months; if stable, consider CT at 2 and 4 years. |
| Subsolid - part-solid | Multiple | Not applicable | ≥ 6 mm | CT at 3-6 months; subsequent management guided by the most suspicious nodule(s). |
| Subsolid - pure ground-glass | Single | Not applicable | < 6 mm | No routine follow-up. |
| Subsolid - pure ground-glass | Single | Not applicable | ≥ 6 mm | CT at 6-12 months to confirm no growth or new solid component; then CT every 2 years until 5 years. |
| Subsolid - pure ground-glass | Multiple | Not applicable | < 6 mm | CT at 3-6 months; if stable, consider CT at 2 and 4 years. |
| Subsolid - pure ground-glass | Multiple | Not applicable | ≥ 6 mm | CT at 3-6 months; subsequent management guided by the most suspicious nodule(s). |
Table based on the incidental nodule algorithm from the NCCN Clinical Practice Guidelines in Oncology: Non-Small Cell Lung Cancer, v6.2026 (pages DIAG-2 and DIAG-3). NCCN updates its guidelines frequently; verify the current version at NCCN.org (free registration required) before basing clinical decisions solely on this table.