Ground-glass density nodules in the posterior segment of the upper lobe of the right lung may be caused by benign diseases such as pneumonia and tuberculosis, or by malignant tumors such as lung cancer. The right lung can be divided into upper, middle and lower lobes, and the upper lobe of the right lung can be divided into apical, posterior and anterior segments. The upper lobe of the right lung is found to have a cloudy slightly dense shadow in chest CT, which is a ground glass nodule. Ground-glass nodules may be caused by benign diseases such as tuberculosis, pneumonia, and charcoal deposition in the lungs, such as inflammation of the lungs, which may result in inflammatory exudation and appear as ground-glass shadows, or malignant tumors such as bronchopulmonary carcinoma and metastatic carcinoma of the lungs, in which the cancerous foci tend to be invasive and infiltrate into the tissues around the foci to produce ground-glass shadows. Milled glass nodules can be categorized into pure milled glass nodules and mixed milled glass nodules according to their density. Mixed milled glass nodules have a higher risk of malignancy, about 63%, while pure milled glass nodules have a malignancy risk of about 18%. The malignant risk of MGN is also related to the size, morphology and calcification of the nodule, etc. Patients are advised to consult their specialists for a comprehensive analysis of the malignant risk of the nodule, and to follow the doctor’s instructions for further examination and treatment.