Surgery is required for 9 mm thymoma. Radical resection through surgery is the most common management option for thymoma, and it is possible to achieve clinical cure status. The size of 9 mm thymoma is still relatively small, and it usually has no invasion to the surrounding tissues, and most of them are benign lesions. However, from the clinical point of view, once thymoma is found, it should be surgically removed as much as possible, mainly because of the fear that the lesion will cause invasion of the surrounding tissues as it progresses, and 9mm thymoma also needs to be treated by surgery. After surgical resection of thymoma, it is necessary to observe the condition of the operated area, and the recovery of myasthenia gravis in some symptomatic thymoma. If you have chest pain, cough or abnormal respiratory condition after surgery, you should consult a doctor for timely observation and standardized treatment after confirming the specific condition.