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Digital Myxoid Cyst

A digital myxoid cyst (sometimes called a mucous cyst) is an entirely benign swelling that occurs on the fingers or, sometimes, the toes. The term cyst is from the Greek kystis meaning a bag or pouch; myxoid and mucoid refer to the jelly-like or slimy contents; and digital derives from the Latin digitus, meaning finger or toe.

Digital myxoid cysts are skin-coloured, reddish or slightly translucent (letting light shine through), and often dimple when pressed. If it is overlying the area where the nail is formed, a cyst may cause a groove to occur along the length of the nail, which can vary in width. Occasionally, slightly sticky, clear, straw-coloured or blood-stained contents may leak out of the cyst, and it may become crusted. Usually, there is just one cyst, but some people may develop more than one, on different fingers.

Causes

Digital myxoid cysts occur most frequently in people in their sixties, and their exact cause is not known. They seem to be related to arthritis of the joint nearest the finger (or toe) nail, resulting from wear and tear, which causes rough outgrowths of the bone and inflammation. The cyst is often connected to the lining of the joint, and is usually located between the joint and the nail.

Digital myxoid cysts are not catching and not a sign of infection. Furthermore, they are not cancerous and will not develop into skin cancer.

Digital myxoid cysts are not hereditary, but arthritis may run in families.

Symptoms

Although there is usually no pain, a cyst may become tender, especially when knocked. There may also be symptoms of arthritis with pain, stiffness and deformity of the joint. Cysts often ‘get in the way’ and their appearance may cause concern.

A digital myxoid cyst is usually easily recognized as a small lump overlying the end finger- or toe-joint, with or without a groove in the adjacent fingernail. The occasional discharge of clear, slightly sticky material from the cyst is also characteristic. If the cyst arises under the nail, the diagnosis is more difficult, and then a scan or taking a sample (biopsy) from the cyst with a local anaesthetic may be needed.

Several different effective treatment options exist for digital myxoid cysts, but they may come back. They may disappear spontaneously.

Treatments

If a digital myxoid cyst does not cause any symptoms, no treatment is required. If treatment is considered necessary, there are a number of options.

Treatments usually not requiring a local anaesthetic

Repeated pressure to the cyst.
Repeated drainage of the cyst fluid using a sterile needle or blade.
Injection of steroids into the cyst.
Freezing of the cyst with liquid nitrogen (cryotherapy).

Treatments requiring a local anesthetic

Scraping the cyst off.
Lifting the area of skin containing the cyst and re-attaching it.
Finding the point of leakage of fluid from the joint by injection of dye into the joint, and then closing that leak.
Cutting the cyst away and applying a skin graft.
Removing the rough, sharp areas on the bone caused by wear and tear from the adjacent joint.
Cauterizing the cyst (infrared coagulation).

What you can do

Digital myxoid cysts may become infected if they are knocked. If a cyst suddenly becomes larger, painful, red and hot, you should see your doctor as these symptoms may indicate an infection and an antibiotic may be needed.