There are benign and malignant mediastinal nodules. Whether a mediastinal nodule of 3cm is benign or not is not only related to the size of the mediastinal nodule diameter, but also related to whether there is invasion of pericardium, heart and other neighboring tissues and organs around the mediastinal nodule, so the possibility of mediastinal nodule of 3cm being benign can’t be directly derived from the size. For mediastinal nodule 3cm, it is recommended to undergo thoracoscopic surgery to remove the mediastinal nodule and send it for pathologic examination, because some benign mediastinal nodules have the possibility of malignant transformation with the development of the disease, which may threaten the patient’s life. If the patient has any discomfort, he should go to the hospital for examination and actively cooperate with the doctor, so as to avoid delaying the treatment, affecting the therapeutic effect, and even threatening the patient’s life.