Pure ground-glass nodules are a sign of lung imaging, which may be caused by infection, tumor and alveolar hemorrhage. 1. Infection: when there are bacteria, mycoplasma, virus, tuberculosis and other infections in the lungs, it may cause the appearance of pure ground glass nodules, and may be accompanied by a rise in inflammatory indicators. 2. Tumor: most patients do not have obvious symptoms in the early stage, but if the tumor grows in the alveolar wall in the early stage and infiltrates along the alveoli to the surrounding tissues, it may also cause the emergence of pure ground-glass nodules in the lungs. 3. Alveolar hemorrhage: if the patient suffers from alveolar hemorrhage due to various reasons, the spread of blood will also cause the appearance of pure ground glass nodules. Therefore, if a patient has pure ground glass nodules, he or she should go to the hospital in time for a detailed examination to find out the cause of the disease and to treat it.