Small pulmonary nodules are generally localized soft tissue lesions 0.5 cm to 1.0 cm in diameter surrounded by air-containing lung tissue that form in the lungs as a result of lung infections, tuberculosis, tumors, and other diseases. In general, its probability of malignancy is 6% to 28%. 1. In order to repair the damaged lung tissue during inflammatory process such as lung infection or tuberculosis, the surrounding naïve connective tissue proliferates to form a granulomatous lung containing a large number of newborn capillaries and fibroblasts and a certain number of inflammatory cells, or in the course of lung infection and tuberculosis and other diseases, cellulose exudates and deposits in the lung tissue to form a fibrous scarred foci, which is manifested as a small nodule in the lung in the imaging examination. 2. Tumor-like hyperplasia in the lungs may form small nodules in the lungs, which may be benign tumors or malignant tumors such as primary lung cancer or metastatic tumors in the later stages of development. Small lung nodules usually require regular outpatient review of chest CT, and when malignancy is suspected, surgery is preferred as early as possible.