Some benign lung nodules may become malignant, and benign lung nodules can become cancerous when stimulated by various factors. Lung nodules are high-density shadows less than 3cm in diameter found on chest CT or X-ray. Benign lung nodules include lung staggers, lung tuberculosis balls, lung fungal balls, lung inflammatory nodules, and atypical verrucous hyperplasia. Most benign nodules do not become cancerous and become malignant. For a small number of benign lung nodules such as atypical neoplastic hyperplasia, they are precancerous lesions, which can further develop into malignant nodules, i.e. lung cancer, when they continue to be stimulated by a variety of disease-causing factors (all kinds of carcinogens). Some inflammatory nodules, under the stimulation of inflammatory factors for a long time, may also become cancerous and turn into malignant nodules. After discovering lung nodules, it is recommended to consult a doctor for a clear diagnosis and quit smoking at the same time.