0:00

This is our last case, a patient

0:02

with a posterior knee mass.

0:03

So we're gonna stay in the popal region.

0:06

Uh, this patient came with outside workup,

0:08

had an ultrasound,

0:10

and they found this, uh,

0:11

vascularized mass at the popal region.

0:14

This was subsequently biopsied

0:16

and, uh, referred to us for further, um, management.

0:22

And so this is the patient's MR Imaging,

0:25

and you can see this pop teal mass.

0:28

And we have a combination. This is a PD fat

0:30

sat, uh, sequence.

0:32

This is a T one fat sat sequence without contrast

0:35

and post contrast sequence here.

0:37

And we can see that there is this enhancing mass in the pop

0:40

teal region between the medial

0:42

and lateral heads of the gastrocnemius muscles.

0:45

You always wanna make sure that you're not dealing

0:47

with something like a popliteal cyst, which is one

0:50

of the more common masses

0:51

that you encounter at the back of the knee.

0:53

Ideally, again, should emanate from

0:55

between the semimembranosus tendon, the medial head

0:58

of the gastroc anemia tendon.

0:59

But clearly this is not a cyst.

1:02

This is a mass that has solid enhancement.

1:05

And, and whenever you're doing tumor imaging,

1:07

it's always important to have a T one fat suppress sequence

1:10

before you give gad

1:11

because you can see that there's some intrinsic T one

1:14

shortening in this mass representing blood products, uh,

1:19

or extracellular meth hemoglobin

1:22

when we're working up any mass too.

1:24

We also want to identify its relationship

1:26

with neurovascular structures.

1:27

So you can see it's, it's intimate with the popliteal artery

1:31

and the vein right in front of it,

1:33

but look what's right behind it.

1:34

We can see that the tibial nerve is also plastered along the

1:38

posterior and posterior medial aspect of this mass.

1:42

Now, given the heterogeneity of this, uh, mass, uh,

1:47

most of you probably know what this entity ended up being.

1:49

This was indeed a synovial sarcoma.

1:53

And some of the imaging features, um,

1:54

include a heterogeneous appearance, sometimes referred to

1:58

as a triple sign, where you have alternating areas

2:00

of bright, intermediate and low signal.

2:02

The bright and intermediate signal represent cystic

2:05

degeneration and blood products.

2:07

And the areas of low signal often represent fibrous bands.

2:10

Not always seen universal universally

2:12

and synovial sarcomas, uh, but can be seen.

2:16

The other sign that you might see is called the bunch

2:18

of grape sign, multiple lobular masses

2:20

that look like, uh, grapes.

2:23

So this patient underwent, uh, neoadjuvant radiation therapy

2:28

to try to get this mass to shrink a little bit.

2:31

And I'll just kind of show you

2:33

what it looked like afterwards.

2:34

Let me give you just the post contrast sequence

2:37

and let me see if I can match these up a little bit.

2:41

So here's the sagittal, pre neoadjuvant.

2:45

Here is the post,

2:47

and you can see in fact it actually grew a little bit.

2:49

The whole point of neoadjuvant, uh, surgery,

2:53

or excuse me, neoadjuvant radiation therapy is

2:55

to reduce the mass to make surgery a little bit easier for

2:58

Our surgical colleagues.

3:00

Now, you could argue is this really bigger

3:03

because you can see that there's more enha non enhancing

3:06

components centrally within this lesion.

3:08

So saying that's a little bit, uh, bigger is um, uh,

3:12

a little bit tricky because clearly this has undergone some

3:15

degree of necrosis, which means that indeed it is responding

3:20

to the neoadjuvant therapy.

3:22

So you always have to kind

3:23

of give a caveat if you say a mass is bigger,

3:26

if there's necrosis.

3:27

You also wanna mention that as well.

3:28

'cause that means that this in some way is actually

3:31

positively responding to neoadjuvant therapy.

3:34

So, um, because of the difficulty of surgery, trying

3:39

to peel this off of the neurovascular structures,

3:41

this patient elected for above the knee amputation

3:44

and unfortunately de developed pulmonary metastasis

3:47

after surgery.