A ganglion cyst is a swelling, balloon-like in shape and on a stalk, that arises from a joint or the sheath of a tendon, and is usually found on the hand or wrist. Inside the cyst is synovial fluid, a clear, colorless substance that becomes gel-like with time. Synovial fluid is the same substance as that found within a joint capsule.
Ganglion cysts are benign, that is, they are non-cancerous, and will not spread to other parts of your body. They may well change in size, depending on how active the joint is, and they are unsightly, but they are not dangerous.
The wrist joint on the back of the hand is the most common place to find a ganglion cyst. They can also occur on the underside, or palm, side of the wrist. Less common sites are on the palm at the base of the fingers, where they tend to be about the size of peas, just below the cuticle on a fingertip, when they are known as mucous cysts, and occasionally on the top of the foot or outside of the knee or ankle.
They are sometimes referred to as ‘bible cysts’. This name comes from the old practice of thumping the cyst with a heavy book in order to break the capsule and release the fluid. Such treatment is not recommended these days due to the risk of inflicting further damage.
Women are slightly more prone than men to getting ganglion cysts, and they tend to be more common in gymnasts. Almost three quarters of sufferers will be aged 20-40. Having osteoarthritis can increase the likelihood of developing a cyst as such a condition often leads to greater amounts of synovial fluid in the joints, which can then leak out.
Although there is no definite known cause, one theory is that an abnormality in the joint capsule, or in the tendon sheath, allows the synovial fluid to escape and form a cyst. Another theory is that a trauma such as a hard blow to the hand causes fluid to form into several small cysts, which then join together to form one larger cyst.
It is generally agreed that the more active a joint is, the bigger the cyst will become and that cysts fill with fluid more easily than they empty.
- A bump that changes in size, increasing with activity and decreasing with rest.
- Oval or round in shape, ranging from soft to firm.
- The bump does not move around.
- Sudden appearance of the cyst, or gradual onset, or disappearance followed by reappearance is possible.
- Many ganglion cysts are painless. It is only if the cyst is pressing on the nerves that pass through the joint that pain is felt.
- Constant, aching pain that is worse with movement.
- Pain, but no visible lump, may indicate an occult, or hidden, cyst.
- Cysts at the base of the finger tend to be very firm, pea-sized and tender under pressure.
- Possible weakness in a finger, if the cyst is connected to a tendon sheath.
- Numbness or tingling of the hand or finger.
Although ganglion cysts are harmless and usually disappear without any treatment, it is a good idea to have it checked by your doctor, just to rule out any other conditions that may produce similar lumps.
Your doctor will ask questions about your general health and lifestyle, and questions relating to your symptoms. You will be asked about the circumstances surrounding the appearance of the bump, any changes you may have noticed, and whether you feel any pain and if so whether that pain is better or worse with movement of the joint.
The bump will be physically assessed, possibly pressed and the joint gently manipulated to see if that causes discomfort. Light might be shone through the lump to see if it is filled with fluid, a procedure called transillumination. Sometimes a needle will be used to aspirate, or withdraw, some of the fluid for evaluation. If the diagnosis is not clear, an x-ray might be needed to rule out other conditions. Ultrasound might be used to determine if the bump is fluid-filled or solid or perhaps caused by a blood vessel. Ultrasound and MRI (magnetic resonance imaging) are useful tools to see occult cysts, if they are suspected.
As most ganglion cysts gradually go away by themselves, conservative treatment is usually followed. Often your doctor will advise you to observe the cyst and return for treatment if your symptoms become worse or you are losing function of the joint.
Do not be tempted to hit the bump with a heavy book as this can cause injury to the hand.
Do not ‘pop’ the bump as this can lead to infection.
Aspiration of the cyst is a common treatment. A numbing agent is injected near the site of the cyst, and then a needle is used to drain fluid. This procedure reduces the size of the cyst and relieves any painful symptoms. However, because aspiration leaves the shell and stalk of the cyst intact, it often refills at a later time. Also, if the synovial fluid has become very gelatinous, it is sometimes difficult to withdraw it through a needle. After aspiration an injection of an anti-inflammatory steroid is administered into the joint, and then a splint applied.
- Over the counter medications can provide relief from pain until the cyst shrinks. NSAIDs such as ibuprofen (Advil), aspirin or naproxen (Aleve), or acetaminophen (Tylenol) will reduce pain and inflammation.
- Avoid movements that make the pain worse.
- Using a splint temporarily will immobilize the joint and allow fluid to drain from the cyst, which will reduce pressure on the nerves and so decrease pain. However, it is not a good idea for the joint to remain immobile for too long.
Surgery is sometimes needed if the cyst continues to be problematic, causing a lot of pain, numbness or tingling or preventing normal function of the hand. Surgery removes the cyst, along with a piece of the joint capsule or tendon sheath. It is the most effective treatment for a ganglion cyst, but does not guarantee that the cyst will not return. After surgery a splint is applied for 7-10 days, after which time movement of the joint is encouraged.
What to look for in a splint:
The best splint for you will depend on the position of your cyst, but it will need to be comfortable and supportive enough to prevent movement of the joint.
Because the exact cause of a ganglion cyst is not known, it is not possible to effectively prevent their occurrence.