There are two main types of pulmonary nodules: benign or noncancerous and malignant or cancerous. The cause of benign pulmonary nodules can be related to inflammation caused by previous lung infections, fungus, rheumatoid arthritis or scar tissues as a result of inflammation in the body. Lung nodules are likely to be benign if:
- You are under the age of 40
- You are a nonsmoker
- The nodule is small less than 3 cm
- There is calcium in the nodule
Growths in the lung that are greater than 3 cm in diameter are more likely to be malignant. Risk factors associated with malignancy include having a history of smoking, exposure to harmful substances such as asbestos, coal dust and other chemicals, as well as being over the age of 50. Cancerous growths usually progress rapidly and may double in size within 4-6 months.