Milled glass nodules may transform into solid nodules. Lung nodules can be categorized into pure ground glass nodules, mixed ground glass nodules and solid nodules based on their density. Pure ground-glass nodules generally grow very slowly, averaging about 2 to 3 mm per year, while ground-glass nodules, including pure and mixed ground-glass nodules, may convert to solid nodules with an increase in the density of ground-glass nodules or an increase in the solid component of mixed ground-glass nodules. The causes of ground glass nodules include inflammatory diseases such as tuberculosis and pneumonia; malignant tumors such as primary lung tumors, infiltrative adenocarcinoma, and micro-infiltrative adenocarcinoma; and benign tumors such as pulmonary arteriovenous malformations, varicose veins of the lungs, and other vascular diseases. If patients are examined for ground-glass nodules, they should have the results carefully evaluated by a professional doctor in time to decide the next step of examination or treatment plan, and if necessary, the ground-glass nodules can be directly removed by surgery to avoid aggravation of the condition.