A ganglion cyst is a fluid-filled sac that can form on the tendons or joints in your hands, wrists, or fingers. These cysts are not harmful or cancerous, and ganglion cysts are common in people of all ages.
Doctors do not know what causes ganglion cysts. It’s believed that, in some cases, trauma may damage the joint tissue. They might also come from a defect in the tendon or joint. It’s thought that this trauma or defect could cause the joint tissue to push outward.
In general, characteristics of a ganglion cyst include:
To confirm that you have a ganglion cyst, your doctor may perform an imaging test like an ultrasound or MRI. He or she may also use needle aspiration. During needle aspiration, your doctor will remove some of the fluid in the cyst to diagnose it.
Because ganglion cysts are typically harmless, your doctor may simply recommend monitoring and waiting. Often, the cysts will go away on their own.
In some cases, your doctor may use a needle to drain fluid from the cyst and inject a steroid into it. If your cyst is causing pain or symptoms that limit your hand movement, you may have surgery to completely remove the cyst.