Neck cysts, also known as cervical cysts, do not necessarily require surgery when they are 39mm, depending on the nature of the cyst and whether there are symptoms of compression. Neck cysts are mostly seen in sebaceous cysts and thyroid cysts. It is currently believed that surgical excision is recommended for neck cysts larger than 20mm. 1. Neck cysts caused by sebaceous cysts often appear as masses under the skin of the neck. If the cysts are not swollen or painful, do not cause airway compression, do not cause respiratory distress, and the patient does not wish to undergo surgery, the patient can undergo regular follow-ups of ultrasound examination of the neck to closely observe whether the cysts are increasing in size. It should be emphasized and reminded that 39mm is already a relatively obvious mass, which will affect the appearance. Surgical removal may be considered for patients who require a better appearance. 2. If it is caused by thyroid cyst, it is generally benign lesions, but it is closer to the trachea, for 39mm thyroid cysts, not only the appearance is obvious, there may be breathing difficulties and swallowing difficulties, at this time, surgical resection is often recommended. It is important to note that when a cyst is found in the neck, it should be actively treated under the guidance of a doctor to clarify the nature of the cyst and whether it will continue to increase in size to prevent compression of the airway.