Pulmonary nodules are round or irregular lesions with a diameter less than or equal to 75px in the lung, which can be single or multiple, with clear or unclear boundaries. The malignant probability of pulmonary nodules with different densities is different. According to nodule density, pulmonary nodules can be divided into three categories: solid nodules, partial solid nodules and ground glass density nodules. At present, the etiology of pulmonary sarcoidosis is not clear, and the possible causes discussed include infection, chemical factors and drugs, allergic reaction, autoimmune and genetic factors.

Clinically, pulmonary nodules can be seen in the following situations:

1. Tuberculosis

Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis infection. The basic pathological changes were inflammatory exudation, hyperplasia and caseous necrosis. Hyperplasia-dominated lesions can be typical tuberculosis nodules with a diameter of about 0. 1mm, and caseous necrosis can occur in the middle of the nodules.

2. Lung cancer

Lung cancer is one of the common malignant tumors, which can be divided into primary cancer and metastatic cancer. Single or multiple nodules with different sizes can be seen in both lungs of lung cancer, which may include solid nodules, partial solid nodules and ground glass nodules.

3. Pulmonary aspergillosis

Invasive pulmonary aspergillosis is mostly localized granuloma or extensive purulent pneumonia with abscess formation. The focus showed acute coagulation necrosis, accompanied by necrotizing vasculitis, thrombosis and bacterial embolism. Its imaging features are multiple wedge-shaped shadows or cavities based on pleura, and the early stage is halo sign, that is, pulmonary nodules.

4. Other circumstances

In addition to the above common conditions, occupational-related pulmonary sarcoidosis includes silicosis and pneumoconiosis, and immune-related pulmonary nodules include Wegener granuloma and alveolar proteinosis.

In short, because the cause of pulmonary nodules is complex, don't panic when you find pulmonary nodules. If a single solid nodule is found in the physical examination, it will be more likely to be benign if it has not changed much all the time. However, it is suggested to continue the follow-up review until the total follow-up time reaches 24 months, and at the same time, try to review under the same CT scanning conditions to avoid the information observation deviation of nodules that may be caused by different conditions. If lung discomfort occurs at the same time, it is recommended to go to a specialist for relevant examination in time to clarify the cause.