Pure ground-glass nodules in the anterior segment of the upper lobe of the left lung are most often considered in respiratory diseases such as interstitial fibroplasia and calcification caused by pneumonia, and can also be seen in lung cancer. Interstitial fibroplasia and calcification caused by pneumonia may form a blurred ground-glass nodule locally, with inflated bronchioles visible inside, manifesting as the vacuolar sign. Such ground-glass nodules are relatively common and small in extent and usually do not require treatment. In patients with lung cancer, the lesion can originate as a ground-glass nodule, although such ground-glass nodules usually have a predominantly solid component, i.e., they do not appear more transparent. After a suspicious ground-glass nodule has been observed, regular follow-up is usually required to monitor for changes in density and size. Pure glass nodules in the anterior segment of the upper lobe of the left lung can also be seen in other diseases, and patients are advised to seek medical attention as soon as possible to avoid delay.