The probability of a 5mm solid nodule in the lungs being benign is relatively high, but it is not possible to accurately determine the chances of the nodule being benign, and it depends on the patient’s specific condition. There are more causes of solid nodules in the lungs, such as pneumonia, tuberculosis and lung cancer. 1. Patients with recent symptoms of lung infection, such as cough, sputum, 5mm solid nodules, patchy shadows, striated changes and other imaging manifestations are considered to be benign inflammatory nodules. 2. If the patient has a history of tuberculosis or has symptoms such as low-grade fever, night sweats (sweating abnormally after going to sleep and stopping after waking up), cough, blood in sputum, and laboratory tests reveal Mycobacterium tuberculosis infection, the presence of a 5-mm solid nodule is most often considered to be due to tuberculosis. 3. If the patient is older, with irritating cough and sputum, and 5mm solid nodules in the lungs with irregular morphology and burrs, then malignant nodules are more likely to be considered. It is recommended that the patient should have a repeat examination of lung CT once every six months to find out whether the solid nodule has increased in size, and if there is a tendency for it to increase in size, the patient should consult the hospital in time for treatment.