Whether a mediastinal nodule of 19 mm needs surgery or not is mainly determined by the condition of the lesion itself and the clinical symptoms. If the lesion is accompanied by obvious clinical symptoms or has the possibility of malignancy, surgical resection is needed; if there are no symptoms, benign lesions can be considered without surgery. 1. If the lesion itself is accompanied by myasthenia gravis, the first consideration is thymoma, which requires surgical resection: posterior mediastinal nodule, accompanied by obvious neurological abnormality, which requires surgical resection for neurogenic tumors; if the nodule is irregular in shape, uneven in density, and continues to grow, which is considered to be malignant, it also needs to be surgically resected. 2. If the lesion does not cause any clinical symptom and is considered as lipoma, cyst or teratoma by overall judgment, it can be treated without surgery and be observed regularly first. If the mediastinal nodule causes obvious chest pain, respiratory limitation, or abnormal nerve function, it is necessary to consult a doctor for observation, and after confirming the diagnosis of the disease, standardized treatment will be carried out under the guidance of the clinician.