0:00

<v ->So we come to the point

0:02

where we have to kind of try to differentiate.

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Differentiate between synovial cysts and ganglion cysts.

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So let's try to take a moment to do that.

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A synovial cyst is filled with fluid,

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lined by synovial cells,

0:18

probably related to elevation of intra-articular pressure.

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And most importantly,

0:23

it communicates directly with a joint lumen.

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A ganglion cyst is different.

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It has gelatinous tissue within its center, okay?

0:34

It has dense connective tissue as a lining.

0:38

It originates not directly from a joint lumen

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but from something else.

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And that something else could be a tendon,

0:46

a tendon sheath, a ligament, a nerve, a vessel.

0:49

I could go on and on.

0:51

From something but not from a joint lumen.

0:54

So just to show you those classic examples here,

0:58

an old one, ugly images,

1:01

but this is rheumatoid arthritis

1:02

of the wrist with a synovial cyst

1:05

communicating with a radiocarpal compartment.

1:09

This is a ganglion cyst

1:11

in the classic location,

1:12

dorsal surface of the wrist,

1:14

above the dorsal scapholunate ligament.

1:18

Not communicating with anything in the wrist joint,

1:22

but communicating typically

1:24

with the ligament itself right here.

1:26

So there's probably mucinous change

1:28

within the scapholunate interosseous ligament.

1:32

So you look at examples like this,

1:33

and fairly easy to tell them apart.

1:36

We see ganglion cysts.

1:39

We see them often around labral tissue.

1:42

You know that well.

1:44

In the glenoid, glenohumeral joint,

1:48

where you look for paralabral ganglion cysts,

1:51

and these occur typically posteriorly or posterosuperiorly,

1:56

and they may involve the suprascapular nerve.

2:00

If they involve that nerve in higher up,

2:03

in the suprascapular notch,

2:05

one often gets the denervation of both

2:07

the supraspinatus and infraspinatus muscles.

2:10

When it involves lower down

2:12

the spinoglenoid notch as shown here,

2:15

it's often the infraspinatus muscle alone

2:18

that shows denervation.

2:21

We see ganglion cysts about the acetabulum.

2:23

Very good clue that there's pathology in that labrum.

2:28

Those ganglion cysts can be extracapsular, intracapsular,

2:32

or in fact,

2:33

both extra and intracapsular.

2:36

We can see them around the knee.

2:38

Here's an interesting one

2:39

extending through the anterior interval,

2:42

into Hoffa's fat bed,

2:43

showing all of signal characteristics including

2:47

the enhancement of the periphery by the gadolinium,

2:50

IV gadolinium, on your right.

2:54

And in the wrist,

2:55

the most common intraosseous site

2:58

for a ganglion cyst is right here.

3:01

It is the lunate bone,

3:03

and more than that is the radial aspect of the lunate bone.

3:07

Now whether this originates in the bone,

3:09

or in the nearby scapholunate interosseous ligament

3:12

could be argued, right?

3:14

And there's probably a debate about it.

3:16

But I want you to look at the classic location

3:19

of a ganglion cyst.

3:21

And on the next slide,

3:22

I'm going to show you why that location is important.

3:25

This is a ganglion cyst involving bone and ligament.

3:29

When we talk about Kienbock's disease at an early stage

3:32

the entire lunate is involved.

3:35

When we talk about ulnocarpal impaction,

3:38

where you have an ulnar positive variance,

3:41

degenerative tears of the triangular fibrocartilage,

3:44

it is the ulnar side of the lunate

3:47

that often shows the changes.

3:49

So you can by distribution,

3:52

separate out these entities

3:54

based upon where the cystic changes are.

3:58

I would also include a word or two

4:01

about intraneural ganglion cysts.

4:04

These probably relate to capsular defects

4:07

in an adjacent joint that allows the joint fluid

4:11

to escape into a nerve,

4:13

one of the articulating branches of a major nerve.

4:18

It is seen throughout the body.

4:20

But I show here with white arrows

4:22

the two most common locations.

4:24

The common peroneal nerve about the

4:26

proximal tibiofibular joint,

4:28

and in the wrist area and elbow area,

4:31

the ulnar nerve.

4:33

The two nerves that are most often involved.

4:36

Here's an example.

4:37

Note the name again, bottom left.

4:39

This is from Spinner,

4:41

showing you the anatomy of the articular branch

4:45

of the common peroneal nerve.

4:47

This is the proximal tibiofibular joint,

4:50

and this is the location of an intraneural ganglion cyst

4:54

arising from that joint.

4:55

Here's the classic location.

4:58

On the MR, note the denervation of the anterior compartment

5:02

of the lower leg.

5:03

So be aware of these intraneural ganglion cysts.

5:07

Here's another one.

5:08

This one is in the tibial nerve.

5:11

I've seen them in the sciatic nerve.

5:15

And so I think you can see these intraneural

5:17

and intravascular ganglion cysts throughout the body.

5:22

So I've defined what a synovial cyst is.

5:25

And I defined what a ganglion syst is.

5:28

Let me show you why there are problems sometimes

5:30

trying to figure out what you're dealing with.

5:33

We often see parameniscal cysts.

5:36

Now the classic thing we're taught is

5:39

the fluid starts in the joint,

5:41

goes through a longitudinal horizontal tear of the meniscus,

5:46

and then the fluid fills the cyst,

5:49

the parameniscal cyst.

5:52

Well, if you define a synovial cyst as fluid communicating

5:56

from the joint lumen into the cyst,

5:59

you'd say that is a synovial cyst.

6:02

So that's why I add the word directly.

6:05

This cyst does not directly communicate

6:07

with the joint lumen,

6:08

it does so indirectly, right?

6:12

And what's interesting about these cysts,

6:15

and I think they are ganglion cysts,

6:17

sometimes they do not communicate with the joint.

6:21

They communicate simply with the meniscus,

6:24

owing to mucinous degeneration, myxoid degeneration,

6:28

the mucinous material passes into the cyst.

6:32

This is the intermediate-weighted MR arthrographic image,

6:36

but look at the T1 weighted image.

6:37

This is a sagittal image.

6:39

There's no gadolinium in there.

6:42

So this is native fluid, right?

6:44

Due to mucinous and myxoid change.

6:47

So I believe a parameniscal cyst is a ganglion cyst.

6:51

But what do I do with this?

6:53

This is a popliteal cyst that's not

6:55

communicating with the joint.

6:57

This is not uncommon,

6:58

particularly in the immature skeleton, right?

7:04

So is this a synovial cyst?

7:06

Is this a ganglion cyst?

7:07

Would you call this bursitis?

7:10

I don't know the answer.

7:11

This is one that, you know, it's hard to do to say.

7:14

And how about this?

7:15

This is something we see frequently.

7:18

Whenever you look at your MR images of the knee,

7:20

one of the last things I do is say

7:22

"Where's the fluid?

7:24

You know, it could be a popliteal cyst,

7:26

but one of the fluid collections that we see rather often

7:29

is intimate with the femoral attachment of the tendon

7:33

of the medial head of the gastrocnemius muscle.

7:37

That is something that we see fairly regularly.

7:41

So what do I call that?

7:42

Do I call that a ganglion cyst or not?

7:44

You know, it's interesting.

7:46

Many years ago,

7:47

people indicated that if you did a knee arthrogram

7:50

and you got delayed images,

7:52

such ganglion cysts would fill with contrast material.

7:56

So some of them communicate with the joint.

7:58

They're a synovial cyst.

8:00

I tend to call these ganglion cysts.

8:03

They occur on the medial side because the attachment

8:05

of the tendon of the medial head is more complex,

8:09

often with two sites of tendon attachment,

8:12

and weak tissue between them.

8:15

And so that's why they occur in that location.

8:19

On the lateral side,

8:20

there's a single attachment of the tendon

8:22

of the lateral head of the gastrocnemius.

8:25

And what do you call this?

8:26

I mean, the hip joint communicates with the iliopsoas bursa

8:30

in 20% of normal persons.

8:32

The frequency goes up when you have elevated pressure

8:36

in the hip joint from a variety of diseases.

8:39

But what do you call this?

8:41

Is this a synovial cyst, a ganglion cyst,

8:43

or is it bursitis?

8:46

So some people believe that synovial cysts

8:48

and ganglion cysts are in fact related.

8:52

That the first stage is a synovial cyst,

8:54

but that over time owing to the continued

8:58

elevated pressure within the joint

9:00

there's degeneration of the tissue

9:02

connecting the joint with the cyst,

9:04

and you eventually end up with a ganglion cyst.