A-Z OF SKIN

Digital myxoid cysts

Digital myxoid cysts

Also known as mucous cyst

What is a digital myxoid cyst?

A digital myxoid cyst is an entirely benign, non-cancerous swelling that usually occurs at the base of the nail on the fingers or toes. Digital myxoid cysts are not “catching” and they are not a sign of infection. They do not develop into skin cancer.

Image reproduced with permission of Dr Anne Howard

What causes it?

The exact cause is not known. The cyst is frequently connected to the lining of the finger or toenail joint and is usually located between the joint and the nail. Arthritis of the joint at the end of the finger or toe probably predisposes a person to developing these cysts.

What does it look like?

Digital myxoid cysts are skin-coloured, reddish or slightly translucent. If a cyst overlies the area where the nail is formed, it may cause a groove to occur along the length of the nail. Sometimes, slightly sticky, clear, straw-coloured or blood-stained contents may leak out of the cyst. Most people usually develop only one cyst. However, some people may develop more than one cyst on different fingers.

The cyst is usually not painful. However, a cyst may become tender, especially when knocked. Occasionally, there may also be symptoms of arthritis with pain, stiffness and deformity of the joint.

Cysts may get in the way and their appearance may cause concern.

Digital myxoid cysts are tender when knocked but only rarely become infected. 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.

How is it diagnosed?

A digital myxoid cyst is usually easily recognised as a small lump overlying the end joint of a finger or toe. There may or may not be a groove present in the adjacent fingernail. If the skin over the top of the cyst is broken, a discharge of clear, slightly sticky material from the cyst is characteristic.

If the cyst arises under the nail the diagnosis is more difficult. The overlying nail is often deformed. A scan or a biopsy (sample taken from the cyst with a local anaesthetic) may be needed.

How can it be treated?

If a digital myxoid cyst does not cause any symptoms, no treatment is required. Small cysts can disappear spontaneously without treatment.

If treatment is considered necessary, there are a number of options.

Without local anaesthetic

  • Repeated drainage of the cyst fluid using a sterile needle or blade

With local anaesthetic

  • Excision of the cyst
  • Injecting dye into the joint to find the cyst and point of leakage from the joint. Then closing that leak.
  • Cauterising the cyst

What is the likely outcome of the condition?

Cysts may recur even after treatment. They may also disappear spontaneously.

This information has been written by Dr Anne Howard

Last updated 06/04/2017