Lung nodule 4mm consider proliferation foci, mainly regular review, good follow-up observation. Lung nodules 4mm, generally consider the past history of lung diseases, such as pneumonia, tuberculosis, etc., in the recovery of proliferation foci, you can not do treatment, pay attention to regular review of chest CT, once every six months or once a year, do a good job of clinical observation. If the review found that the small nodules in the lungs continue to grow larger, combined with the professional doctor’s treatment advice, you can consider thoracoscopic surgical resection treatment. Therefore, small lung nodules 4mm are mainly considered to be proliferative foci left behind by lung diseases, and there is no need to worry too much. During the regular review period, if you find that the small nodules in the lungs are abnormally large, it is recommended that you cooperate with the professional doctor as soon as possible to improve the relevant examinations, such as bronchoscopy, lung puncture biopsy, etc., to clarify the size, shape, and nature of the nodules, and to formulate the next step of the treatment plan in a timely manner.