Digital mucous or myxoid cyst
A mucous or myxoid cyst arises from degeneration in the connective tissue on the top of the last segment of the finger. It may connect with the joint at the end of the finger.
The cyst has a smooth shiny surface and is to be found at the base of the nail or within a centimetre of so. It often causes a groove in the nail, a few millimetres across which extends the length of the nail. The cyst's size may vary. Jelly-like sticky fluid may be expressed from it (sometimes tinged with blood).
What causes these cysts?
There appear to be two variations. The first is a form of focal mucinosis, a condition characterized by abnormal deposits of mucopolysaccharides (mucins) in the skin. Strictly speaking, it shouldn't be called a cyst as it does not have a surrounding capsule, and is better termed a
pseudocyst. The other variation arises from extension of the lining of the finger joint and is due to osteoarthritis – a type of ganglion.
Treatments which may be successful include:
- Repeatedly pressing firmly on the cyst
- Squeezing out its contents (make a hole with a sterile needle)
- Cryotherapy (freezing)
- Steroid injection
- Sclerosant injection
- Surgical removal
Unfortunately, mucous cysts often recur, whatever treatment is used.