Lung nodule is defined as a nodular shadow of increased density in the lungs with a diameter of less than 3cm, and the possible causes of lung nodules in 80 year olds include: inflammatory nodules, tuberculosis, lung cancer, lung metastases, etc. 1. Inflammatory nodules: various lung infections can form tissue exudation in the lungs and manifest as lung nodules on imaging, in addition, lung inflammatory foci are wrapped by hyperplastic fibrous tissues can also form lung nodules. 2. Tuberculosis: Mycobacterium tuberculosis into the blood can form a blood dissemination type of tuberculosis, the formation of diffuse multiple nodular lesions in the lungs. The caseous necrotic foci of tuberculosis are wrapped by proliferating fibrous tissues, which can form tuberculosis balls and may also be manifested as pulmonary nodules. 3. Lung cancer: primary lung cancer can be manifested as nodular shadow in the lungs when the initial volume is small, which is mostly a single nodule, and multiple nodules can also be formed when the primary lung cancer forms intrapulmonary dissemination. 4. Lung metastases: Many malignant tumors in other parts of the body can easily transfer to the lungs through blood channels to form lung nodules, such as endometrial cancer, choriocarcinoma, osteosarcoma, etc., which are mostly multiple small nodules. If there is a history of malignant tumor and lung nodules appear, the possibility of metastasis should be considered. It is recommended that 80-year-old people should go to the hospital as soon as possible to get a clear understanding of the nature of the lung nodules and be treated accordingly under the guidance of professional doctors.