Solitary pulmonary nodules

A solitary pulmonary nodule (SPN) is a single, well-defined lesion, ≤ 30 mm in diameter, that is completely located in the pulmonary parenchyma.

• Perform a detailed clinical evaluation.

• Review any previous imaging (if available) to evaluate for changes.

• Obtain a thin-slice CT chest if not already available.

• Identify nodule size and other characteristics.

  • Features suggestive of malignancy include irregular margins, larger size, upper lobe location.

  • Features suggestive of other etiologies include calcifications (see “Differential diagnosis of pulmonary nodules”).

• Determine the risk of malignancy of a solitary pulmonary nodule.

The risk of malignancy can be determined by clinical evaluation and/or predictive modeling and helps guide management and follow-up.

• The most extensively validated model is the Mayo Clinic model in which 6 predictors of malignancy are combined in a logarithmic equation to calculate the risk.

• Risk categories

  • Low: < 5% (typically, patients with low-risk predictors)

  • Intermediate: 5–65% (typically, patients with a mixture of high-risk and low-risk predictors)

  • High: > 65% (typically, patients with high-risk predictors)

• Patients with any of the following characteristics should be excluded from this approach and require case-by-case management:

  • Age < 35 years

  • Immunocompromise

  • Active known primary cancer

  • Symptomatic patients

• Options typically include biopsy, further imaging, or long-term surveillance with serial imaging.

Solid nodule > 8 mm

• High risk: Obtain a surgical biopsy and start treatment based on the results.

• Intermediate or low risk: Obtain a PET-CT scan.

  • Positive PET-CT: Obtain a surgical biopsy.

  • Negative PET-CT and intermediate risk: Obtain a nonsurgical biopsy.

  • Negative PET-CT and low risk: Observe with serial CT scans.

Solid nodule ≤ 8 mm

• Most patients are assessed with serial CT scans.

• Surveillance frequency is determined by the patient's malignancy risk and nodule size.

Surveillance is optional for low-risk patients with a solitary pulmonary nodule < 4 mm in diameter.