The appearance of nodules in the lungs may be caused by malignant tumors, infections, pulmonary hemangiomas and so on can be caused. 1. Malignant etiology: Lung nodules may appear after cancerous changes in lung tissues. Common causes include lung adenocarcinoma, lung large cell carcinoma, lung squamous cell carcinoma. Lung nodules can also be caused by metastasis of cancerous lesions in other organs to the lungs, and common causes include chest tumor, colon cancer, melanoma and so on. 2. Benign causes: Lung infections can cause pulmonary nodules, common causes include tuberculosis, fungal infections of lungs, etc. Lung hemangioma and lung malformation tumor can also cause lung nodules. There are many causes of lung nodules, so it is recommended to go to the hospital to find out the causes and get timely treatment.