A ganglion cyst is simply a fluid-filled sac. It can be visible from the outside or buried deep underneath the skin.
Sometimes it causes symptoms like soreness and pain; other times patients have no idea it’s there.
What is a mucous cyst?
Ganglion cysts in the finger are often called “mucous cysts”, because of the mucous-like, or jelly-like clear fluid inside them.
These cysts are filled with joint fluid that has partially thickened. The jelly looks a lot like hair gel when it squishes out of the cyst in surgery!
The most common location for these is in the middle finger. They usually don’t happen in patients younger than 45 or 50 years old.
This type of arthritis is more common in women than men, and usually doesn’t happen before age 40. Fractures and other trauma to the thumb joint may put you at risk for developing arthritis in the future.
What’s inside the cyst?
The fluid inside the cyst is joint fluid. Every joint produces this fluid normally. In arthritis, the worn-out joint produces more fluid than usual. The fluid builds up and eventually forces its way through the joint lining and through the tendon fibers on top of the finger. This forms a cyst that you can see underneath the skin.
Sometimes the skin has a normal thickness, and you just see the bulge of the cyst below the skin.
Other times the cyst puts so much pressure on the skin that the skin thins out and becomes translucent – you can almost see through the skin at that point!
These cysts can be tiny or huge – they can have a single chamber, or multiple lobes and chambers.
Where do mucous cysts come from?
The cysts almost always come from a mildly arthritic joint. In other words, the joint may not be worn out enough to be painful, like most people think arthritis would be. But the joint is worn out enough to make more fluid than normal.
I always take an xray of the finger when I see one of these cysts. Sometimes the xray will show big bone spurs and other signs of arthritis. Most of the time, though, the xray appears almost normal; just a little extra narrowing of the joint more than normal.
Can they go away on their own?
Sometimes they pop on their own – other times they last for years.
Usually, they go up and down in size with activity.
Some of my patients are adventurous and try to puncture them on their own before they come and see me. It’s amazing how often they come back, despite the multiple self-surgery attempts.
Nail deformity and fingertip ganglion cysts
Many patients see a deformity or groove in the nail along with the cyst.
This happens because the tissues that grow a nail are very close to the cyst. The cyst pushes on these tissues, called the nail bed, and the nail can’t grow normally. Grooves in the nail usually resolve completely once the cyst is removed in surgery.
How are fingertip ganglion cysts treated?
In almost every situation, it’s safe to leave these cysts alone. There’s no medical reason to take them out.
However – if the cyst has ruptured on its own, or the patient has repetitively punctured the cyst with a needle, trying to get rid of it, I recommend surgery.
Since the ruptured cyst comes from the joint, a hole in the cyst and in the skin provides a direct path for bacteria to get from the skin down into the joint and even into the bone.
It’s rare to see an infected joint from one of these ruptured cysts, but it is possible, and not worth the risk.
Pain is another reason patients want these removed. But I always caution them that the pain could be coming from the arthritis in the joint and not the cyst itself. Getting rid of the cyst may not take their pain away.
The surgery involves opening up the skin over the cyst and cutting out a small window in the joint lining. I then scrape the edges of the joint where the cyst comes from. I try to find the root of the cyst and destroy it so it can’t come back.
Surgery is done as an outpatient, under local anesthesia plus a little sedation through an IV. You wear a tiny finger splint on the tip of the finger for about 10 days until the stitches come out. It’s safe to take the splint off for showering and typing during that time. After 10 days, you can use the finger as much as you want for normal activities.
Can mucous cysts come back after surgery?
There’s always a theoretical possibility of the cyst coming back. I’ve seen two come back in 8 years of doing hand surgery, so it’s rare. Since the arthritis is still there after the surgery, the cyst can come back. The only way to permanently remove the arthritis is to fuse the joint, which is a pretty radical step for most patients with a mucous cyst.