What Is a Ganglion Cyst??>
Ask the Experts

What Is a Ganglion Cyst?

by Jeanine Barone  

Q: What is a ganglion cyst, and how is it treated?

A: A ganglion cyst is a firm, gelatinous-fluid-filled sac located just under the skin. It’s actually an outgrowth from the lining of a nearby joint or tendon sheath, to which it remains connected by a stalk. Such cysts typically occur in the wrist (usually the upper side) or on the top of the foot; less often, they develop in the shoulder, spine, or knee. Ganglion cysts have been called “Bible bumps” because historically people would use a heavy book, such as a Bible, in a possibly successful but likely painful attempt to flatten them.

The exact cause of ganglion cysts isn’t known. Some of them appear to stem from acute trauma, such as a wrist sprain or a stubbed toe. But more commonly they are believed to develop from cumulative microtrauma due to overuse (from frequent piano playing, for example, or use of a jackhammer). The cysts are more common in women and in people under age 40.

Some ganglion cysts cause no problems, but others can become painful and uncomfortable. A cyst that compresses a nerve, for instance, can result in tingling, burning, or numbness; a cyst that presses on a joint or tendon can cause aching and possibly restrict motion in the joint. A ganglion cyst in the foot can be especially painful because your shoe may press on it.

If you think you have a ganglion cyst, see your doctor, who will feel the bump (it should move a bit under the skin) and likely shine a bright light on it to help rule out a solid tumor such as a lipoma (a benign fatty tumor). A light will often shine through a cyst but not through a solid tumor. In some cases, an ultrasound or MRI may be done to confirm the diagnosis.

If the cyst causes no symptoms, your doctor may just monitor it over time. More than half of ganglion cysts eventually resolve on their own, though this can take a while—even years. If the cyst is on your foot, it may help to wear shoes that don’t rub against it or to place a pad inside your shoe to reduce pressure on it.

For a cyst that causes discomfort or bothers you aesthetically, a needle aspiration can be done to drain out the jellylike fluid. The cysts have a high rate of recurrence after this procedure, however. Another option is surgery to remove the cyst as well as the stalk that connects it to the joint or tendon sheath. Surgical treatment is highly effective, and complications (such as infection, reduced range of motion of the involved joint, and injury to nerves or tendons) are rare.

Whatever the treatment, the typical overuse that led to the development of the ganglion cyst should also be dealt with.Otherwise, in the case of nonsurgical treatment the cyst may recur, and in the case of surgical excision a new cyst may form.

This article first appeared in the UC Berkeley Wellness Letter.

Also see Is That a Cyst, Zit, or... Furuncle?