Ganglion cysts are noncancerous lumps that most commonly develop along the tendons or joints of your wrists or hands. They also may occur in the ankles and feet. Ganglion cysts are typically round or oval and are filled with a jelly-like fluid.
Small ganglion cysts can be pea-sized, while larger ones can be around an inch (2.5 cm) in diameter. Ganglion cysts can be painful if they press on a nearby nerve. Their location can sometimes interfere with joint movement.
The cause of ganglion cysts is not known. One theory suggests that trauma causes the tissue of the joint to break down, forming small cysts that then join into a larger, more obvious mass. The most likely theory involves a flaw in the joint capsule or tendon sheath that allows the joint tissue to bulge out.
Although ganglion cysts can be unilobulated, they are most often multilobulated, with septa made from connective tissue separating the lobes or cavities.Thornburg points out that because there is no epithelial lining of the cyst wall, a ganglion cyst is not a true cyst and, because of this histologic observation, the theories of synovial herniation or synovial tumor formation are not supported and may be disputed.
Hyaluronic acid predominates the mucopolysaccharides that make up the fluid within the cyst’s cavity, whereas collagen fibers and fibrocytes make up the wall lining. The development of these cysts is histologically observable beginning with swollen collagen fibers and fibrocytes, followed by a degeneration and liquefaction of these elements, a termination of degeneration, and, lastly, a proliferation of the connective tissue, resulting in a border that is dense in texture.
The lumps associated with ganglion cysts can be characterized by:
- Location. Ganglion cysts most commonly develop along the tendons or joints of your wrists or hands. The next most common locations are the ankles and feet, although these cysts can occur near other joints as well.
- Shape and size. Ganglion cysts are round or oval and usually measure less than an inch in diameter. Some are so small that they can’t be felt. The size of a cyst can fluctuate, often getting larger when you use that joint for repetitive motions.
- Pain. Ganglion cysts usually are painless. However, if a cyst presses on a nerve — even if the cyst is too small to form a noticeable lump — it can cause pain, tingling, numbness or muscle weakness.
A physical exam is often all that is needed to diagnose a ganglion cyst.
- Your doctor may get further confirmation by using a syringe to draw out some of the fluid in the cyst (needle aspiration) or by using ultrasound. An ultrasound picture is made as sound waves bounce off of different tissues. It can determine whether the bump is fluid-filled (cystic) or if it is solid. Ultrasound can also detect whether there is an artery or blood vessel causing the lump.
- Your doctor may send you to a hand surgeon if the bump is large or solid or involves a blood vessel (artery).
- Magnetic resonance imaging (MRI) is used to see the wrist and is very useful for ganglions. One drawback to this diagnostic method is the cost of the procedure.
Ganglion cysts are often painless, requiring no treatment. In fact, in many cases, doctors recommend a watch-and-wait approach. But if the ganglion cyst is causing pain or interfering with joint movement, your doctor may recommend:
- Immobilization. Because activity can cause the ganglion cyst to get larger, your doctor may recommend wearing a wrist brace or splint to immobilize the area. As the cyst shrinks, it may release the pressure on your nerves, relieving pain.
- Aspiration. In this procedure, your doctor uses a needle to drain the fluid from the cyst. Before the aspiration, your doctor might inject an enzyme into the cyst to make the jelly-like contents easier to remove. After aspiration, some doctors inject a steroid into the cyst to reduce the chances of recurrence.
- Surgery. If other treatments haven’t worked, surgery may be an option. The procedure removes the cyst and the stalk that attaches it to the joint or tendon. Rarely, the surgery can injure the surrounding nerves, blood vessels or tendons. And the cyst can recur, even after surgery.