An 11mm ground glass nodule can be the result of a malignant tumor or a benign condition. If it is malignant, it is more serious, if it is benign it is usually not serious. Lung nodules are lung masses greater than or equal to 3cm found on chest CT. Lung nodules may be caused by malignant tumors such as bronchopulmonary carcinoma, or benign diseases such as lung misshapen tumors, rheumatoid nodules, tuberculosis, etc. The risk of malignancy is different for nodules of different sizes, densities, and morphologies. Generally, 11mm nodules have a higher risk of malignancy, about 15% to 20%. Lung nodules can be categorized according to their density into solid nodules, pure ground-glass nodules, mixed ground-glass nodules, and the latter two together as ground-glass nodules. Milled glass nodules have a high risk of malignancy, especially mixed milled glass nodules. If the 11mm MGN is caused by malignant disease, it is more serious and may be life-threatening, such as lung cancer; if it is caused by benign disease, such as misshapen tumor, it can be improved or cured by timely treatment. It is recommended that patients with 11mm MGN should consult a specialist at a regular hospital for further evaluation or follow-up.