A bulging bulge found on the back of the hand, wrist, dorsum of the foot, ankle, etc. in a hemispherical, round or oval shape, this may be a tendon sheath cyst, which is a common benign tumor. Tendon sheath cysts, so what is tendon sheath? The tendon sheath is like a knife sheath, it is a dense tissue that surrounds certain long tendons and increases the gliding ability of the tendon, it is divided into an outer fibrous layer and an inner synovial layer, which is divided into a dirty layer and a wall layer, and synovial fluid exists between the two layers. What is a tendon sheath cyst? A tendon sheath cyst is a cyst formed when some dense tissue on the joint capsule, ligament or tendon sheath that surrounds the tendon is injured, resulting in fluid accumulation in the synovial cavity or local degenerative deformation. How do tendon sheath cysts form and what are their manifestations? It is formed when chronic strain causes increased friction between the tendon’s slide and its outer sheath, resulting in increased accumulation of synovial fluid. From the appearance, it is a bulging lump above the skin surface, round or oval, varying in size, with a soft texture at first, which can have a fluctuating feeling, or a hard rubber-like texture and tough feeling, with a full and smooth surface. Generally, there are no obvious symptoms, but a few people have soreness, pain, or self-conscious weakness, and when the cyst is stuck on the nerve, there will be corresponding discomfort symptoms. It can occur at any age, but is usually seen in young and middle-aged people, more in women than in men. Where are tendon sheath cysts likely to occur? The extremities are the most common areas for tendon sheath cysts, with the wrist, fingers and dorsum of the foot being the most common areas, both of which are superficial and easy to detect. When they occur in the wrist and ankle, they may cause symptoms due to pressure on the enlarged nerves of the cyst. In addition, there are specific terms for tendon sheath cysts in specific areas, such as those occurring in the buttocks called sciatic tubercle cysts and those in the back of the knee called popliteal fossa cysts. What are the treatments for tendon sheath cysts? Some cysts can disappear on their own after growing for a period of time and will not recur; some cysts are small, asymptomatic and have no obvious effect on appearance, so they are left untreated and temporarily observed; when the swelling continues to increase in size, or when symptoms appear due to pressure on the surrounding tissues, or when it affects the aesthetics, active treatment is required. 1. conservative methods: ① local braking, limiting injurious movements; ② massage, pressing through the cyst to release and absorb the cyst fluid (3) Extraction of jelly-like fluid from the cyst and injection of hormones into the cystic cavity, etc. to make its inner wall adhere. 2. Surgical methods: Patients whose conservative treatment is ineffective and who have recurrent recurrence can consider surgical removal of the cyst. Are all tendon sheath cysts suitable for surgery? Yes, the chance of the cyst absorbing and disappearing on its own is very, very low. Compared to conservative treatment, surgical treatment has a lower recurrence rate and all tendon sheath cysts are suitable for surgical treatment. What are the advantages of surgery for tendon sheath cysts in plastic surgery? Tendon sheath cysts are body surface tumors and are a major area of treatment in plastic surgery. Traditional tendon sheath cyst removal surgery requires the application of a tourniquet to assist in reducing bleeding in the operative field. Under local anesthesia, the discomfort of pain from prolonged hemostasis and the patient’s irritation negatively affect the surgery. Plastic surgery applied swelling anesthesia technique to cystectomy, with long anesthesia duration, less bleeding in the operation area, no tourniquet assistance, and the patient can chat with the surgeon in the awake state.