Ganglion cysts are small, benign, fluid-filled sacs. They are found attached to joints, most commonly on the wrist, and present themselves as small lumps under the skin.
The causes of ganglion cysts are still not known. The cysts appear to grow from joints like a balloon on a stalk and tend to develop in areas where a joint or tendon naturally bulge out of place.
There are, however, three main categories of risk factor:
Age and sex: ganglion cysts can affect anyone at any time, but they are most commonly found to occur in females aged 20-30
Joint or tendon injury: areas injured in the past are more likely to develop ganglion cysts
Overuse: people who vigorously use certain joints 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.
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. 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 (2.5 centimetres) 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. But 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.