Frosted glass nodules in the lungs with a diameter of 4mm are not normal, but most are not serious and require regular follow-up. Clinically, nodules smaller than 5mm are called micronodules, so a 4mm ground glass nodule falls into the category of micronodules. Micro-milled glass nodules grow slowly and can be followed up regularly. If they are reviewed once a year, they can be checked once every two years if there is no change. Some tiny nodules may disappear within three months, six months, or even a year. These are called transient ground-glass nodules, and most are caused by inflammation, hyperplasia, edema, or small hemorrhages in the lungs. Some of them may remain unchanged for a long time or for life, while others will gradually increase in size or change in shape, and the disease may progress to lung cancer gradually. Active treatment, such as surgical resection, is needed. In conclusion, if you find ground-glass nodules in the lungs, you should consult a doctor in time and listen to the advice of a professional doctor.