Characteristics of Malignant Pulmonary Nodules

Clinical and Radiological Characteristics

The American Thoracic Society recommends that pulmonary nodules with spiculated margins, size greater than 8 mm, location in the upper lobe, volume doubling time less than 400 days, and absence of benign calcification are considered malignant 1, 2
Age is a risk factor for malignancy, with an odds ratio of 1.04-2.2 for every 10-year increase 1, 3
Current or former smoking is a risk factor for malignancy, with an odds ratio of 2.2-7.9 1, 3
A history of extrapulmonary cancer is a risk factor for malignancy 1, 3
Hemoptysis is a risk factor for malignancy 3
Family history of lung cancer is a risk factor for malignancy 3
The diameter of the nodule is a risk factor for malignancy, with an odds ratio of approximately 1.1 for every 1 mm increase 1, 3
Spiculated or irregular margins are a risk factor for malignancy, with an odds ratio of 2.1-5.7 1, 4, 5
Location in the upper lobe is a risk factor for malignancy 1, 3
Pleural indentation is a risk factor for malignancy 1, 3
Volume doubling time less than 400 days is a risk factor for malignancy 1, 3
Pleural retraction is a risk factor for malignancy, with a likelihood ratio of 1.9 4, 5
Vascular sign is a risk factor for malignancy, with a likelihood ratio of 1.7 4, 5
Bronchogram or pseudocavitation is a risk factor for malignancy 4, 5

Diffuse, central, laminated, or "popcorn" calcification is a characteristic of benign nodules, with an odds ratio of 0.07-0.20 1, 3, 8
Peripheral location is a characteristic of benign nodules 1, 3
Smooth or polygonal margins are a characteristic of benign nodules, with a likelihood ratio of 0.2 4, 5
Combination of round shape, smooth margins, and low attenuation is a characteristic of benign nodules 4, 5
Presence of intranodular fat is a characteristic of hamartomas, which are benign tumors 4, 5
Stability for at least 2 years is a characteristic of benign nodules 4

In patients with multiple nodules, each nodule should be evaluated individually 6, 7
Treatment should not be denied without histopathological confirmation of metastasis 6, 7
The prevalence of malignancy in coexisting nodules less than 12 mm in patients with known primary lung cancer is 3-11% 2, 9