The presence of multiple dense nodular shadows in both lungs, pathologic changes detected by taking x-rays of both lungs, by CT or MRI or by doing imaging of both lungs. This means that there is some disease in the lungs, more commonly benign lesions, including typical bacterial infections, such as Staphylococcus aureus, Klebsiella, Pseudomonas aeruginosa, etc., but also tuberculosis caused by Mycobacterium tuberculosis, which results in the development of multiple inflammatory nodules. It also includes malignant tumors, such as bronchopulmonary carcinoma and alveolar cell carcinoma, which can be detected by taking respiratory secretions and culturing the suspected pathogens. Under the guidance of bronchial fiberoptic endoscopy, high-density nodule biopsy can also be taken to do pathological examination to clarify the nature of the nodule and the etiology of the disease.