ToolsCalculators
Solitary Pulmonary Nodule (SPN) Malignancy Risk Score (Mayo Clinic Model)
Pretest probability that an indeterminate lung nodule is malignant.
Solitary Pulmonary Nodule (SPN) Malignancy Risk Score (Mayo Clinic Model)
Age
years
Smoking status
Any history of cigarette smoking.
History of extrathoracic cancer
Nodule diameter
mm
Spiculated margin on CT
Nodule location
Complete the fields above to see the result.
When to use
- Estimating the pretest probability of malignancy for a newly discovered, radiologically indeterminate solitary pulmonary nodule.
- Deciding between surveillance, PET-CT, biopsy, or resection alongside society (e.g. Fleischner) guidance.
Formula
p = e^x / (1 + e^x), where x = -6.8272 + (0.0391 x age) + (0.7917 if current/former smoker) + (1.3388 if extrathoracic cancer >5 years earlier) + (0.1274 x diameter in mm) + (1.0407 if spiculated) + (0.7838 if upper-lobe location).
Pearls and pitfalls
- Derived from a cohort of surgically resected and clinically followed nodules 4-30 mm at a single referral centre before PET-CT was widely available.
- Complements, but does not replace, dedicated nodule-management guidelines (e.g. Fleischner Society) which incorporate nodule growth and patient risk more granularly.