Had a friend ask me about an unusual bump on his wrist. It was soft and moveable and not painful or infected. A cyst is a fluid filled sac of fibrous tissue from smaller than a centimeter to the size of a marble. Some cases may be larger, but most are non-surgical and benign. Also known as “bible bumbs” becuase the treatment used to consist of hitting them with a bible. Though they are malformations of joint cartilage the greatest danger with these is if the “bumb” begins to hamper wrist motion and hand function by its size. However, ganglion cysts rarely continue growing in size and are of the non-cancerous, non-malignant type. Puncturing the fluid sac is not recommended as this rarely reduces it’s size. Why they develop is somewhat of a mystery, but some have theorized that the cysts are common around joints and that some joint material herniates or is allowed outside of the joint but not back in. They can be alarming and can give the impression of a tumor. Please have a doctor examine any lesion that are questionable.
Some guidelines you can use to differentiate a ganglion cyst from other tumors. If the bumb is moveable and doesn’t feel attached to the bone, skin or muscle in particular then it may be a cyst. Cancerous tumors usually involve a growth that attaches and invades skin, muscle or bone (even blood). So immoveable growing bumbs are a concern. Cysts normally stay the same shape and size throughout life and usually show no signs of new growth while cancerous tumor are, by definition, a proliferation of cells and so continue growing at variable rates.
Cysts also occur other places on the body, including the back of the knee (known as Baker’s cysts). But the overwhelming majority of cysts occur on the dorsum (back) of the wrist and hand to the tune of about 80%. A sac that is filled with pus is not called a cyst but an abscess and is caused by an infectious agent (for instance bacteria entering a wound).
Mostly cysts are just an eyesore and a cosmetic anomaly and no cause for alarm. But cysts may appear elsewhere on the body and are distinct from fibromas (soft fibromas are called skin tags usually appearing on the neck) and have no irritation like rashes and insect bites, in fact they are sensitive to pain only when compressing one of the superficial nerves of the skin. This means that cysts are not sensitized to feel pain and so usually lateral movement of the cyst is elicits no feeling, but direct pressure is painful.
All in all cysts aren’t to much of a worry and I say surgery is an option if they are painful or restrict function.