Ganglion cysts are small, benign, fluid-filled sacs. They can be attached to joints or arise from a tendon sheath, which is the covering over the tendon.
They most commonly affect the wrist and hand, but they can appear on the ankle, foot, or knee. They form small lumps under the skin.
The cysts are not cancerous, and they are usually harmless. If they cause pain, make it hard to use the joint, or are especially unsightly, they may be removed.
Ganglion cysts mostly affect people between the ages of 15 and 40 years, and women are more susceptible than men. They are quite common, but relatively little is known about them.
Fast facts about ganglion cysts
- Ganglion cysts are non-cancerous, but how they form is unclear.
- Half of all ganglion cysts disappear without intervention.
- The fluid within the cysts is similar to that contained within synovial joints.
- Draining or surgically removing the cysts may prevent their return.
- They most commonly occur next to the wrist joints, but they can affect the feet.
What is a ganglion cyst?
Ganglion cysts form a benign lump that often goes away on its own.
Ganglion cysts were first mentioned as long ago as Hippocrates, but even now, they remain something of a mystery.
They appear, often on the back of the hand, as a round or oval-shaped lump that is filled with fluid. They can range from the size of a pea to that of a golf ball.
Beneath the skin, the cyst resembles a water balloon on a stalk.
A cyst does not pose a significant medical threat, but it can sometimes be troubling.
If it pushes on a nerve, it can cause pain or make some movements difficult. It can sometimes be a cosmetic problem because of the size.
Ganglion cysts can usually be recognized by their features.
Location: They are always near a joint, most commonly the top or back of the wrist, but possibly on the palm side of the wrist, on the palm at the base of a finger, or on the top of the end joint of a finger. They may appear on the top of the foot, on the ankle, or sometimes the knee.
Pain: They may or may not be painful. If they press on a nerve, there may be pain.
Shape and size: They are roughly circular and less than 2.5 centimeters (cm) across, or up to the size of a golf ball. Some are very small. They may be felt as lumps under the skin, or they may not be noticeable at all.
They may be soft or hard, and they should move freely under the skin.
A ganglion cyst that occurs at the base of the finger may feel like a pea-sized lump under the skin.
If the cyst is on a finger joint, it may involve an arthritic spur, the skin over the cyst may be thin, and there may be a groove down the fingernail that is just above it.
Sometimes, the region around the cyst can feel numb, and grip strength can be reduced in the affected hand.
What causes a ganglion cyst is still not known, but they may happen when connective tissue breaks down around a joint. They tend to be attached to an underlying joint capsule or a tendon sheath.
They appear to grow from joints like a balloon on a stalk, and they tend to develop in areas where a joint or tendon naturally bulges out of place.
Risk factors seem to include:
Age and sex: Ganglion cysts can affect anyone at any time, but they are most commonly found to occur in females aged 15 to 40 years.
Joint or tendon injury: Areas injured in the past are more likely to develop ganglion cysts.
Overuse: People who use certain joints vigorously are more likely to develop ganglion cysts. Female gymnasts, for instance, are particularly prone.
Osteoarthritis: People with wear-and-tear arthritis in the joints nearest to the fingernail are more likely than others to develop this type of cyst.
Trauma: They may result from a single incident or from repeated small injuries.
Exactly what leads to the formation of ganglion cysts is not fully understood.
Here are three possible causes, all related to joint stress.
- Joint stress might lead to a split in the joint capsule that surrounds the joint. As a result, synovial fluid leaks into the tissue around the joint. Reactions between the fluid and tissue then create the thick cystic fluid and the cyst wall.
- Joint stress may cause connective tissue to break down in the area. If fluid then accumulates, a cyst may eventually form.
- Joint stress could cause mesenchymal cells to stimulate mucin secretion.
Mucin is a constituent of mucus, and mesenchymal cells are cells that can develop into a number of different cell types.
The fluid within a ganglion cyst is similar to the joint’s normal synovial fluid. A ganglion cyst appears to develop when the fluid leaks out of the area around the joint and collects in a sac.
How or why this happens is not entirely clear.
A ganglion cyst’s fluid is thicker than normal joint fluid. It mainly consists of hyaluronic acid, a common compound in connective tissue. It also contains lesser amounts of glucosamine, globulins, and albumen.
There are three theories about where the fluid comes from.
- It may start in the joint itself, with fluid being pumped into the cyst by movement of the wrist.
- It might happen when a site outside the joint degenerates, resulting in cyst formation.
- Mesenchymal cells within the cell walls might produce the fluid.
One individual might experience all of these changes.
To diagnose a ganglion cyst, the doctor will usually shine a light through the cyst to see if its contents are transparent or opaque. The liquid will be clear and thick.
An X-ray, ultrasound, or MRI can help rule out other more serious outcomes, such as cancer, arthritis, or other joint or bone problems.
A routine x-ray may not show up a ganglion cyst, and the x-ray will be normal unless there are changes related to arthritis.
What are the causes and types of arthritis?
Find out more about arthritis, a common joint problem
If a ganglion cyst causes no discomfort or pain, it is often left as it is. Around half of ganglion cysts resolve without intervention, but it can take years for them to completely disappear.
Watchful waiting: Many ganglion cysts go away without treatment, but if the cyst is on the foot or ankle, the person may need to wear shoes that do not rub or irritate the cyst. Placing a pad inside the shoe may help.
Immobilization: Moving the affected area might increase the cyst’s size. Applying a splint or brace to the area will limit movement. This may cause the cyst to shrink in size.
If there are other problems, for instance, if the cyst is pressing on a nerve and causing pain, treatment is possible.
If the cyst is painful, an over-the-counter (OTC) medication may help, such as ibuprofen.
Wearing softer or open shoes, inserting padding, or changing how the shoes are laced may help.
People are not advised to follow a traditional remedy of hitting the cyst with a heavy object, as this is unlikely to solve the problem and it may cause further damage to the surrounding area. After this, it usually recurs.
Individuals should not “pop” the cyst, as this can lead to infection and it is unlikely to remove the cyst.
If the cyst is large or if it causes further problems, removal may be necessary.
Aspiration: The fluid inside a cyst is similar to that which naturally occurs in joints. Removing it may permanently remove the cyst. A doctor may start by injecting an enzyme into the cyst. This breaks down the fluid into a less thick consistency, making it easier to drain. The cyst may come back, however, if the “root” remains.
Open surgery: The surgeon makes a small incision and removes the cyst, together with the stalk.
Keyhole surgery: The surgeon makes a small incision and inserts a camera into the affected area. The camera will guide the procedure. This is less painful than open surgery and there is a low recurrence rate. However, it has been reported that the rate of recurrence is still nearly 30 percent.
After surgery, the patient should keep the area covered and protect it from accidental bumps.
If the cyst was on a hand or wrist, they may need to wear a splint for a few days.
OTC painkillers may help if there is pain. There may be discomfort, bruising, and stiffness, but these should resolve fairly soon.
Keeping the extremity raised can help prevent swelling. If discomfort persists, the person should see their doctor.
Removing the cyst does not a guarantee that it will stay away. Surgery makes it less likely to recur, but it can lead to complications and permanent scarring.