What is a mucoid cyst on a finger and how is it removed?

Transcript

Let's take a look at mucoid cyst surgery. A mucoid cyst is a small ganglion cyst that arises from the joint called the distal interphalangeal joint, or DIP joint, which is right out here near the nail bed. Let's take a look. You can see here just a bump right over the joint.

And over here you can, on the left it looks just a simple bump right over the, over the joint, whereas on the right side there's actually a nail groove happening. And why is that? Because the cyst, although it communicates with the, with the joint, it actually has tracked and is formed out here over the, the germinal nail matrix, which puts pressure on the area that forms the nail, leading to a linear or depressed groove of the nail deformity, which actually will resolve, um, after surgery in many cases.

So let's take a look now at actually what's happening under the skin. This shows a nice schematic of the distal interphalangeal joint between the distal phalanx at the tip and the middle phalanx right here, and out of the joint capsule from underlying arthritis pops a cyst, almost like a little mushroom type, uh, structure filled with this jelly, and it can fluctuate in size as the fluid can drain back and forth between the joint and the cyst.

So also associated with this, as I said, was, is degenerative arthritis, but let's take a look at the bone spurs that can form right underneath the cyst. And these are important, as we'll talk about in a little bit, to take these out to lower the recurrence rate when surgery happens.

Okay, so let's look at now at this next image, which is actually an x-ray. When you come in, when you have a bump on your finger, well, you'll think it's just a, a little mass, and why get an x-ray? Well, the reason we want to get an x-ray is to, is to see if there's an underlying bone spur from that underlying arthritis.

This patient has mild arthritis, but in the circle area where the arrow is pointing, you see a little [ __ ] of bone or calcification, and that's a bone spur. So when we go in to remove that cyst, it's important to take that out. In some patients an MRI will be obtained.

As you can see from this next image, the mucoid cyst labeled, arrow is pointing to this white structure right over the, over the distal interphalangeal joint or DIP joint, and this is filled with fluid. Show, it shows up on this MRI as a white structure, again just to further, um, diagnose what's going on in there and distinguish this mass from others.

So after this, after the MRI is taken, usually this is a surgical cure. In this patient you can see a large bump right over the distal interphalangeal joint. There's real, no, there's no nail plate abnormality. So in, in a lot of patients they will have seen a dermatologist or other doctors, will have gotten multiple cortisone injections or sucking the fluid out of the, out of the, the cyst. That can provide temporary relief, but usually that's not curative unless you go in there, remove the cyst and take out the spurs.

Let's take a look. We're going to cut down through the skin. You can see this magnified view, great picture of this large cyst that you just saw before the skin was cut open. But now you can see multi-lobulated, all these different like balls together, all filled with this gelatinous fluid, fluid. Over on the top side you see this white structure running along here. That's the extensor tendon, that's the tendon that straightens the finger.

So we be very careful to go right off the edge of the tendon, take out the cyst, and then there's going to be a little bone spur, as there was in this patient. We just nibble that off, a little biter, and then we sew the skin together. So those stitches are going to be in. After this little dressing, the stitches will be in for about 10 days. You come back to the office after the initial wound check 10 days later to get those stitches out.

You'll start ranging motion right away after surgery to prevent stiffness, therapy in some cases. Overall this is highly successful surgery, about a 95% success rate, and there's about a less than a 5% chance of recurrence. For more on this condition and many other conditions, please check out our website.