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Dr. P. here with an interesting case of a

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3 00:00:04,340 --> 00:00:07,800 56-year-old woman that is complaining

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of pain in the lateral aspect of the

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ankle, rule out peroneus brevis tear.

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We have before you a T1 spin echo

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and a water-emphasized proton

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density fat suppression sequence.

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And we've got extensive soft tissue involving the

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intra-articular space and some of these foci are

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rather dark, even though we don't have a gradient

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echo, which would be wonderful to have had one.

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Now, these dark areas might represent

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calcification, but they're not.

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There is some ossification over here near

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the medial malleolus, might also represent

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pseudorosis or hemocytorin, which it

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does, and the process is rather diffuse.

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It's everywhere, and that's significant because

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we're gonna subset and divide this entity.

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Into different categories which

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affect the surgical management.

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And one of these categories is the

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diffuse variant of this which is

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PVNS, pigmented villonodular synovitis.

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And then we have to decide, do we have it

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in the lateral, the medial, the anterior,

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the posterior, or the subtalar compartment?

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Because if there's going to be a synovial

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resection, they have to know how many

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portals of entry they're going to

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use to try and get this out of there.

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In severe cases, they may use something

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like a beta emitter, and try and reduce

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the burden of this lesion by injecting

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the beta emitter into the joint.

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I believe it's yttrium that they use for

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that purpose, and then they may try and

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debulk it afterwards or just simply try

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and control it with radionuclide therapy.

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Another interesting aspect of this

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disease is its pressure erosions.

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The T1, I think, is particularly revealing in

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showing you these pressure erosions right there.

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And they're, and they're very etched,

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almost like the pressure erosions

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that we see from adjacent gouty tophi.

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And this combined with this heterogeneous low

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signal intensity makes the diagnosis of the

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synovial metaplastic subset known as PVNS.

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What are some other synovial metaplasias?

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Well, you've got lipoma arborescens,

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where you proliferate fat.

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You can even have synovial hemangiomatosis.

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There is some debate about whether that's

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part of the metaplastic family, but certainly

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synovial chondromatosis, also known as

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multifocal synovial chondromatosis, is a synovial

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metaplasia, and those may go on to ossify.

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Now when we're dealing with PVNS, we

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said compartmentalizing and localizing

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the burden of disease is important.

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Occasionally, you'll get an

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isolated lesion in the joint.

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And this is known as localized PVNS.

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Some have referred to it as localized intra-

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articular giant cell tumor of tendon sheath.

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And you do get localized giant cell tumor of

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tendon sheath in an extra-articular space,

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especially in the finger, as many of you know.

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You can also get isolated multifocal,

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say two, three, or four different areas.

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They look like boulders.

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And they're certainly bigger than the metaplastic

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condition known as synovial chondromatosis.

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So when you look at the boulders of PVNS

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multifocal type, this is the diffuse type by

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the way, they're going to be about that big.

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And when you look at the signal intensity

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and the size of synovial chondromata, they're

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usually gray, so I hate to use gray because it's

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hard to see, but I'm going to use it anyway.

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I'm going to draw over bone just for giggles.

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And it's about, they're about this size.

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They're usually under a centimeter in size.

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Let's try it on the fat.

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And then if they, if they ossify,

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they may appear very white.

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So, you know, if we take our white color, you may

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actually see like a marrow-like character to them.

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So they may look like this.

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So, it's not appropriate to call it synovial

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osteochondromatosis; it's more appropriate to

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call it synovial chondromatosis with ossification.

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As you know, cartilage is going to

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have this signal intensity right here,

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gray, and so those are going to look

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gray on most of the pulsing sequences.

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One of the take-home messages for this

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disorder is if you aspirate it, it will

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bleed, and sometimes you will see a

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hemorrhagic effusion associated with it.

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Your job

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is to make the diagnosis, which in this case

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is pathogenic, and also to help the surgeon

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through where the portals of entry should go

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for purposes of resection, and if the patient

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is a candidate for resection, if not, they

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may have to undergo radionuclide therapy.

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Diffuse PVNS pressure erosions as part

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of the synovial metaplastic family.

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Dr. P out.