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The link will be provided in the chat box.

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Today we are joined by Dr. Deborah

0:31

Baumgarten for our Noon Conference on

0:33

an approach to retroperitoneal masses.

0:35

Dr. Baumgarten is an abdominal and abdominal

0:38

radiologist focusing on ultrasound and CT of

0:41

benign and malignant GU and GI conditions.

0:45

She is active in service and education,

0:48

mentoring trainees and junior faculty.

0:50

She's active in radiology societies

0:52

and reviews for multiple journals.

0:54

She's also a baker and volunteer.

0:58

Dr. Baumgarten has also contributed an excellent

1:00

Mastery Series course on scrotal imaging for

1:03

MRI Online and is available along with over 100

1:06

other courses to MRI Online premium members.

1:09

We'll add the links to the relevant courses in

1:11

the chat box along with membership information.

1:14

We truly appreciate Dr. Baumgarten

1:16

joining us today and for being a part of

1:18

our MRI Online faculty. A reminder that there

1:21

will be a Q and A session at the end of

1:22

the lecture for any questions you may have.

1:25

Please use the Zoom Q and A feature to

1:27

submit your questions, and we'll get to

1:28

as many as we can before our time is up.

1:30

With that being said, we welcome you Dr. Baumgarten.

1:33

Please take it from here.

1:35

Thank you, and I will.

1:37

Share my screen now, share, screen share, and

1:44

hopefully you're all seeing the correct screen.

1:46

I am gonna be talking about an

1:48

approach to the retroperitoneal mass.

1:50

I am a professor of radiology

1:51

at the Mayo Clinic in Florida.

1:53

I have a couple of disclosures.

1:55

One was already mentioned.

1:56

I am a speaker for MRI Online, and I did

1:59

record a Mastery Series on the scrotum,

2:01

which includes anatomy, masses,

2:04

vascular issues, trauma, and so forth.

2:06

It's really a case-based review.

2:09

I am also on the scientific advisory board

2:12

for a company called Voyager Pharmaceuticals.

2:14

It's a company that's developing barium

2:16

and iodine products, so it's not really

2:18

relevant to our conference today.

2:20

In the next 50 minutes or so, I will be discussing an

2:23

approach to retroperitoneal masses with an emphasis on

2:27

first determining whether a lesion is retroperitoneal

2:30

or maybe it's not, what its organ of origin might be,

2:33

and I'll be going through various signs and trying

2:36

to come to a reasonable differential diagnosis.

2:39

Also using characteristics of a lesion.

2:42

And then if you can't be definitive about

2:44

what your diagnosis is, at least giving

2:47

you some tools to suggest whether the lesion

2:49

is more likely to be benign or malignant.

2:52

I welcome you to put questions in the Question

2:55

and Answer box as we go along, and if I happen

2:58

to notice a relevant question, I might just

3:00

interrupt myself and answer it as we go.

3:02

But I promise you, if I miss your question

3:05

during the talk, I will try to get

3:07

to as many again as I can at the end.

3:10

So let's first discuss, um, how we decide

3:13

if a lesion is retroperitoneal or not.

3:16

So let's take this lesion to determine

3:19

if a mass is retroperitoneal.

3:20

There are several clues that we can use.

3:23

The first has to do with displacement of organs.

3:27

Are retroperitoneal organs anteriorly displaced?

3:30

And in this case of a dedifferentiated sarcoma, the

3:35

descending colon is displaced anteriorly and medially.

3:40

A second clue is whether the mass surrounds

3:42

retroperitoneal organs or the great vessels,

3:45

and in this case, the left kidney is surrounded

3:49

partly by the mass, so we can be pretty confident.

3:52

This is actually a retroperitoneal mass.

3:57

How about this case?

3:59

This is a very large fatty mass.

4:02

The ascending colon is displaced

4:04

anteriorly and medially.

4:07

The duodenum is displaced medially.

4:10

So this is also another case of a

4:12

retroperitoneal mass, but in this case,

4:14

this is just a benign retroperitoneal

4:17

lipoma.

4:20

What about this large mass?

4:22

The ascending colon is actually

4:24

pushed backward, not forward.

4:27

There's a plane with a kidney, so we are

4:30

suspecting this is not retroperitoneal.

4:33

On this coronal image, you can see there's a

4:35

normal right ovary, and this turned out to be

4:39

a really large borderline left ovarian tumor.

4:43

So this was not retroperitoneal,

4:45

but peritoneal in origin.

4:50

In this case, we have a, a large

4:52

mass in the right upper quadrant, and

4:55

the spleen is posteriorly displaced.

4:58

The aorta is posteriorly displaced, and the

5:02

left kidney is also posteriorly displaced.

5:05

So we are confident this is really not a

5:07

retroperitoneal mass that we're dealing with.

5:10

So from what might this large mass arise?

5:13

Well, another clue is that the

5:15

stomach is very compressed here,

5:20

very compressed, and this turned out to be

5:23

a very large gastrointestinal stromal tumor.

5:27

So again, we've gotta use all the clues about what

5:29

organs are being compressed, moved, and so forth.

5:34

What about this lesion?

5:37

This case very nicely demonstrates

5:39

involvement of the great vessels.

5:41

In this case of lymphoma, we're lifting the

5:44

aorta and we're surrounding the renal arteries.

5:48

This has sometimes been referred

5:50

to as the floating aorta sign.

5:53

With the aorta floating above the vertebral

5:55

body column surrounded by a mantle of soft

5:58

tissue, and this is very common in lymphoma.

6:01

Again, another retroperitoneal process.

6:04

In addition, you see that both kidneys are involved,

6:08

and this is also pretty very typical of lymphoma.

6:13

What about determining an organ of origin?

6:16

There are several signs that we can use.

6:19

The first one I'll discuss is the beak or claw sign.

6:22

This is when there is deformity of the organ

6:25

of origin into what's called a beak or claw

6:28

shape, and it implies that the organ that's

6:31

forming the shape is the organ of origin.

6:35

So here's a beak sign on ultrasound with an

6:37

oncocytoma and two beak signs of renal cell

6:41

carcinoma on CT, both arising from the left kidney.

6:49

If an organ is adjacent to a mass, but the

6:52

interface is linear and there's no deform-

6:54

ity into a beak or claw sign, it may mean

6:59

that that mass may not arise from that organ.

7:02

So this is a case of a pancreatic pseudocyst,

7:05

and there is no beak sign, but rather a

7:08

more linear interface with the left kidney.

7:11

So we can say that this is not arising from the

7:13

left kidney, but just compressing the left kidney.

7:19

Or in this case of a retroperitoneal sarcoma,

7:22

abnormal soft tissue surrounds the left lower pole

7:26

of the left kidney, but there's really no beak signs.

7:29

So we're not suspecting that this is arising

7:31

from the kidney, but arising from the

7:33

retroperitoneal space behind the kidney.

7:40

In this case, we see that the stomach is

7:42

laterally and a little bit posteriorly displaced.

7:45

So we're already thinking that we are not

7:48

dealing with a retroperitoneal mass, and in

7:51

fact, the pancreas is also posteriorly displaced.

7:54

Another clue that this is probably

7:56

not retroperitoneal. So when we look

7:59

really closely, we can see that there's

8:01

actually a beak sign with the liver.

8:04

And this turned out to be a

8:05

very large hepatic adenoma.

8:10

The next sign we'll talk about is what's called the

8:13

embedded organ sign, which implies that if an organ is

8:16

inside a mass, it is likely the origin of that mass.

8:20

In this case, we can see that there's a

8:22

dilated pancreatic duct in the pancreatic

8:25

tail here, and again in this image as well.

8:29

But the body of the pancreas is completely embedded

8:33

by this very large soft tissue mass, which was

8:36

confirmed as — no one is probably doubting — to be

8:39

a pancreatic adenocarcinoma. But in case you are

8:43

wondering whether it arose from this organ or not,

8:46

again, the embedded organ sign can help you decide.

8:51

How about this case?

8:53

There's a large fat-containing mass.

8:57

In the retroperitoneum, the right adrenal

8:59

could not be seen separate from this

9:01

mass and was assumed to be engulfed.

9:04

There's a straight interface here with the left

9:06

kidney, so there's — excuse me, right kidney —

9:09

so there's no beak sign with the kidney.

9:12

This was a very large

9:14

right adrenal myelolipoma, and this is also exhibiting

9:18

a sign that's called the Phantom Organ sign, which

9:22

is when the organ of origin is no longer discernible

9:24

because it's been completely engulfed by a mass.

9:30

Here's another example that

9:31

I like of the Phantom Organ.

9:33

Sign. This,

9:35

in this case, we really can't

9:36

discern the right kidney.

9:39

It's completely engulfed by this

9:40

very large retroperitoneal mass.

9:43

Unfortunately, this patient could not get IV

9:45

contrast because his creatinine was elevated.

9:48

We did get an ultrasound, and I think you can

9:50

appreciate some normal right renal parenchyma here.

9:54

And then a little bit of hydronephrosis

9:56

of the upper pole, which you can

9:57

kind of faintly see on the CT here.

9:59

And then this coat of mass that's

10:01

just incredibly infiltrative.

10:04

Now, we really can't make a specific diagnosis

10:06

on this without a biopsy, but this turned

10:08

out to be a Rhabdoid renal cell carcinoma,

10:11

one of the more, uh, aggressive infiltrative variants.

10:15

But another example of the Phantom Organ sign,

10:18

again, when you can't really discern the organ of

10:20

origin because it's so engulfed by

10:23

a mass that it is likely the organ of origin.

10:28

In this case, however, we can see that the left

10:30

kidney is clearly just pushed aside by this

10:33

retroperitoneal mass, so it's not the organ of origin.

10:37

And this again, was just another

10:39

retroperitoneal sarcoma. We can see that it

10:42

almost has a beak sign with the psoas muscle.

10:45

So you kind of wonder if, if there's a psoas muscle

10:47

origin here or if it's actually just pushing on

10:50

the psoas muscle, but clearly retroperitoneal.

10:54

The feeding artery sign is another topic I'll talk

10:57

about, which implies that if you can find an artery

11:01

that's supplying the mass, the organ that that

11:04

artery is coming from may be the organ of origin.

11:07

And one of the nicest examples I

11:09

have is of a right pelvic mass.

11:12

Can we tell if this is adnexal or uterine in origin?

11:16

Well, here's the uterus here with,

11:18

you can see the endometrium there.

11:21

And here's the mass, and there is no

11:23

beak or claw sign with the uterus.

11:26

It's just next to the uterus.

11:28

So again, is this adnexal or

11:30

is it arising from the uterus?

11:33

If we put color flow on, we can see that

11:36

there are vessels bridging between the

11:38

uterus and this lesion, which just turned

11:41

out to be an exophytic uterine fibroid.

11:44

So this is not an adnexal mass,

11:45

but rather a uterine mass.

11:49

An example in the abdomen here of the feeding

11:52

artery sign, we can see that there is a fatty

11:56

retroperitoneal mass here, but we can see that

11:59

there's an artery supplying this mass that it is

12:02

arising from the kidney, so that even if we can't

12:06

find a beak or claw sign or any kind of divot

12:09

in the kidney, that lets us know that this

12:11

fatty mass is arising from the kidney.

12:13

The feeding artery sign is going to help us determine

12:16

that this is an angiomyolipoma arising from the

12:19

kidney and not a retroperitoneal liposarcoma.

12:27

Now, what if you don't have any of these signs, so

12:29

you're really not sure where the mass is coming from?

12:32

You don't have a beak or claw sign.

12:33

You can't find a feeding artery.

12:36

Again, what if none of these gives

12:37

you a clue to the organ of origin?

12:40

You need to think about what else gives

12:41

rise to masses in the retroperitoneum.

12:44

So we consider that there are nerves

12:46

in the retroperitoneum, there are

12:48

vessels, there are lymphatics.

12:50

So we can look at determining an organ

12:53

of origin based on other things, knowing

12:56

what else lives in the retroperitoneum.

13:01

So we take this example. We have

13:03

a retroperitoneal mass here.

13:06

It's separate from the left adrenal gland, which we

13:09

can see a nice fat plane on several of the images.

13:14

It's also separate from the pancreas.

13:16

Again, we can see a fat plane

13:18

between this mass and the pancreas.

13:21

It's separate from the kidney and from the

13:23

retroperitoneal vessels, so we're dealing

13:26

with something that's pretty non-specific.

13:28

It could be arising from a nerve.

13:30

It doesn't seem to be arising from any of

13:32

the vasculature in the retroperitoneum,

13:35

and this turned out to be a paraganglioma.

13:40

In this particular case, we have a retroperitoneal

13:43

mass that's inseparable from the inferior vena cava.

13:51

On multiple of these images, it pushes the

13:54

pancreas anteriorly — here, here, and here.

13:59

And there's no beak sign with the pancreas.

14:02

It really looks more like

14:03

there's a beak sign with the IVC.

14:05

So one of the things that we need to consider when a

14:07

mass is intimately associated with the IVC and looks

14:11

relatively aggressive, as in this case, is that we're

14:14

dealing with a sarcoma arising from the IVC itself.

14:21

Now let's think about some differential

14:24

possibilities based on the components of a mass.

14:28

So you might be able to come to a

14:30

reasonable differential if you know or

14:32

suspect what organ something is arising

14:35

from, and then look at what it's made of.

14:38

So the first thing we'll talk about

14:40

is fatty components, because it's

14:42

probably the easiest to tackle.

14:44

So we have here a fat-containing mass.

14:47

You can see the edge of the mass here.

14:50

It's arising from the adrenal, so it's a myelolipoma.

14:54

And if we look carefully, we can see the limbs of the

14:56

left adrenal are being splayed by this fatty mass.

15:03

Fat-containing masses that, in this case, have a

15:06

beak sign with the kidney and probably some feeding

15:10

arteries as well, when they contain fat like this.

15:13

And we're confident that they are

15:15

arising from, and not just next to, the

15:16

right kidney are angiomyolipomas.

15:20

So again, this is not necessarily a difficult

15:22

diagnosis in this case because we have this

15:25

lovely divot from the kidney and the beak

15:27

sign telling us it's arising from there.

15:32

When we have non-specific fat-containing masses in

15:34

the retroperitoneum, we have several possibilities.

15:37

And we've seen this case already in, uh, the,

15:41

the first couple of slides where we have very

15:43

homogeneous, nearly entirely fat lesions.

15:47

So there might be a couple of

15:48

little vessels running through here.

15:50

But we really don't see any other component at all.

15:53

I will tell you that this little smudge here

15:55

was just the bottom of the right kidney.

15:57

So this is not a soft tissue component, but you

16:00

need to look very carefully through the entirety

16:03

of this mass to make sure that there are no soft

16:05

tissue components, and when they are entirely

16:07

homogeneous like this, they're retroperitoneal lipomas.

16:13

Another possibility for a fat-containing mass in

16:16

the retroperitoneum is to determine whether you notice

16:19

that the kidneys are completely surrounded by the fat.

16:26

There may be some linear septations, but

16:28

no real soft tissue masses within this.

16:31

And again, the fact that it is completely

16:33

surrounding the kidneys gives us a clue that

16:36

this is lipomatosis of the retroperitoneum.

16:39

Another benign process.

16:44

Now we're starting to get into some

16:45

fat that looks a little dirtier here.

16:48

We know, again, this is retroperitoneal

16:50

because we are pushing the ascending colon forward.

16:55

We're pushing the kidney backwards a little bit.

16:57

In this case, there's no retroperitoneal fat posterior

17:00

to the kidney, so it is displaced posteriorly.

17:02

We're pushing all of the peritoneal bowel loops

17:05

here, so we are dealing with a retroperitoneal mass.

17:09

But it has a lot of these streaky things.

17:11

This was a liposarcoma,

17:13

probably pretty well-differentiated because

17:15

there's no large soft tissue components,

17:17

just these linear soft tissue components.

17:20

And again, although this might look a

17:21

little bit like the lipomatosis of the

17:23

last case, it's not surrounding the kidney.

17:27

This is a true retroperitoneal mass

17:29

that is separate from the kidney.

17:34

How about this one here?

17:36

We do have fat that is surrounding the left kidney.

17:39

Here's the kidney sitting here,

17:41

and we are surrounding the kidney.

17:43

So we might think, at first glance, this

17:45

is kind of weird, unilateral lipomatosis.

17:48

Lipomatosis tends to be bilateral,

17:49

but it may be a little asymmetric.

17:51

But again, we've gotta look really carefully.

17:54

There are multiple soft tissue

17:56

masses within this fatty mass.

18:00

This is just the psoas muscle here, but linear

18:04

streaks and frank soft tissue lesions.

18:07

So this is another liposarcoma, but it is

18:10

less well-differentiated than the last case.

18:14

Now there are biopsy techniques and things

18:16

that our pathologists can do now to help

18:19

us differentiate benign lipomas from liposarcoma,

18:22

from dedifferentiated liposarcomas.

18:25

There are various things that they now

18:27

have in their arsenal, which will help us.

18:29

So biopsy of these lesions may also help you decide

18:33

if you're unsure whether it's a benign lipoma or if

18:36

it's a liposarcoma, and if management will change.

18:39

If knowing that ahead of

18:40

time, then it's always a good—

18:43

idea to do that.

18:45

Now, I did notice that a question came in.

18:47

Can we always localize all retroperitoneal

18:49

masses and determine the origin?

18:52

And I'm gonna say as we go through these cases, that

18:54

sometimes it's easier and sometimes it's harder.

18:56

And of course, I'm gonna show you the cases

18:59

where it was relatively easy to make the

19:01

diagnosis because I have all the clues present.

19:03

It is not always easy, which is why.

19:07

It's good to use every clue.

19:09

So again, looking at which way organs are moving,

19:12

you can tell hopefully whether something is

19:14

retroperitoneal or not, which is going to give you

19:17

a different idea of the organ of origin, which are

19:19

the organs are retroperitoneal or which are not.

19:22

But then as we go through these

19:23

components, that will also help you.

19:26

The next component I'd like to mention is calcium.

19:30

When we consider masses that contain calcium and

19:32

they arise from the adrenal, we need to consider

19:36

myelolipomas, which can have calcifications,

19:38

and you can see some fat in the lesion.

19:41

There is some soft tissue, which is

19:43

the myelo part, not the lipoma part,

19:45

and then multiple small calcifications.

19:50

Calcium and lesions.

19:51

Also, again, another one

19:52

arising from the adrenal gland.

19:55

We see a relatively homogeneous low-attenuation

19:58

mass when we compared pre- and post-contrast images.

20:02

This did not show any enhancement, so this

20:05

is an adrenal cyst, which can sometimes

20:07

also have calcifications, and we can see

20:10

that the limbs of the left adrenal here are,

20:13

are being splayed around this adrenal cyst.

20:18

Other masses that contain calcium

20:20

arising in the retroperitoneum can

20:23

be malignant fibrous histiocytoma.

20:25

We can get extraskeletal osteosarcomas.

20:29

Um, those are also possible.

20:33

And another question just came in,

20:35

um, how can we differentiate really

20:36

large myelolipomas from sarcomas?

20:39

Sometimes it's really hard to do that.

20:42

Um, myelolipomas.

20:44

In my experience, tend to push the kidney,

20:47

maybe not surround the kidney so much.

20:50

Um, again, you can look for the,

20:52

the, where it's infiltrating.

20:55

Um, sometimes again, you just have to go to a biopsy.

20:58

You're also likely to have a,

20:59

a large myelolipoma removed.

21:02

Just because it's probably symptomatic

21:04

based on mass effect and other things.

21:06

So if it's important to know ahead of the surgery,

21:08

'cause it might change the surgical approach to

21:10

know if something's a myelolipoma or a liposarcoma,

21:13

then a biopsy in those cases is gonna help.

21:18

Other masses that contain calcium.

21:20

Here we see a relatively

21:22

heterogeneous right para-aortic mass.

21:25

It's got calcification in it, mostly

21:26

soft tissue, maybe a few areas of

21:28

necrosis, which we'll talk about soon.

21:31

Um, the history in this case really helps,

21:33

'cause this patient had

21:35

a history of a left testicular mass, so

21:38

this turned out to be metastatic teratoma.

21:41

But if this were the first presentation in a

21:43

male patient with a heterogeneous retroperitoneal

21:46

mass along the aorta with calcification, teratoma

21:50

would be something you'd wanna think about.

21:53

And again, even if you had homogeneous lymph nodes in

21:56

the retroperitoneum, especially unilateral in a male,

22:00

you really want to think about a testicular primary.

22:03

You also wanna note that there's a right ureteral

22:06

stent here that we can see, and this is a clue

22:10

that this is probably adenopathy as pushing the

22:13

ureter laterally, which is one of the things that

22:16

retroperitoneal adenopathy, because it'll be along

22:19

the aorta and cava, will push the ureters laterally.

22:26

Here's another large lesion with some calcium in it.

22:30

This one turned out to be a very large schwannoma.

22:32

So again, a kind of a non-specific mass arising

22:35

from nerve sheath in the retroperitoneum.

22:39

One of those where it might be hard to determine

22:41

the organ of origin other than to dismiss things

22:44

are surrounding it, like the kidney.

22:46

Um, we know it's retroperitoneal

22:48

because it's pushing the colon forward.

22:51

We don't have a beak sign with the liver.

22:53

It pushed a little bit of the pancreas, so we can

22:55

look at the other organs around it and determine it

22:58

doesn't seem to be arising from any particular organ.

23:01

And that's again, when we go to their, alright, is

23:03

it arising from a blood vessel, from a nerve, or is

23:06

it a non-specific sarcomatoid sort of lesion that's

23:09

just arising from the retroperitoneal soft tissues?

23:14

Um, I'm gonna skip one of these questions that

23:17

just came up and move along for a second here too.

23:21

The next component I'd like to talk

23:22

about is necrosis or hemorrhage.

23:25

Um, these are usually associated

23:27

with very high-grade malignancies.

23:28

Think about things like liposarcomas, leiomyosarcomas,

23:32

other sarcomas, but you can have necrosis or

23:34

hemorrhage in benign lesions

23:37

if there are very vascular benign lesions.

23:41

And in this case, this mass did have

23:42

central necrosis, which we can see.

23:46

It's separate from the kidney.

23:49

Or was separate from the kidney.

23:51

Um, and it turned out to be a paraganglioma,

23:55

which is a benign lesion in most cases, but can

23:58

have necrosis centrally because they're very

24:00

vascular and they outgrow their blood supply.

24:04

This one, I don't think anyone has a difficulty

24:07

determining that this is arising from the left kidney.

24:10

Given that the left kidney is fairly engulfed.

24:12

We see a little normal renal parenchyma here.

24:15

Here, but this lesion is smack dab in the middle of

24:18

the left kidney, and the lesions that have necrosis

24:22

of renal origin are usually renal cell carcinomas.

24:25

So again, this is not a difficult lesion to make a

24:27

diagnosis, but the fact that there is necrosis is

24:31

certainly gonna lead you down the malignancy rather

24:34

than this even being entertained as anything benign.

24:41

Necrosis or hemorrhage, again,

24:42

in a renal cell carcinoma.

24:43

We can see this area of hemorrhage here

24:45

in a lesion that has, is very cystic.

24:49

It's probably outgrown its blood supply.

24:51

It's hemorrhaged.

24:52

It's probably rapidly increased in size.

24:55

There's a little bit of soft tissue

24:56

component here, and there were other

24:58

soft tissue components in this as well.

25:00

But this turned out to be a

25:01

very large renal cell carcinoma.

25:06

Again, necrosis or hemorrhage.

25:07

In this particular lesion, we

25:09

have some areas of necrosis.

25:11

It completely engulfed the adrenal gland.

25:14

On the right side, there's a fat plane

25:16

with the kidney, so something else

25:18

to think about is metastatic disease.

25:21

Again, another malignancy, and not uncommon, of course,

25:25

with lung primaries to go to the adrenal gland.

25:31

The next component we'll talk about is if

25:33

you have relatively homogeneous soft tissue.

25:35

So we're not seeing necrosis, we're not

25:37

seeing fat, we're not seeing calcium,

25:40

but rather homogeneous soft tissue.

25:43

So in this case, we have this very homogeneous mass.

25:47

In fact, bilateral masses, right?

25:51

Uh.

25:52

Retroperitoneal behind the IVC and then surrounding,

25:56

partly surrounding the aorta, lifting it up.

25:59

And again, this was another case of lymphoma.

26:03

Lymphoma tends not to be necrotic or have areas

26:07

of calcification unless it's been treated.

26:10

So it would be helpful to know if you do see a

26:14

necrotic retroperitoneal mass, if the patient's

26:16

had any treatment at all, because once you start

26:18

treatment, lymphoma can show areas of necrosis.

26:24

Here's another case.

26:26

We have a homogeneous

26:27

retroperitoneal soft tissue mass.

26:29

It involves the pancreatic head.

26:33

So is this an adenocarcinoma of the pancreas?

26:37

Well, we wanna look more carefully.

26:39

Another clue is that the pancreatic

26:42

duct you see here is not dilated, and

26:45

the pancreatic tail is not atrophic.

26:48

If this were an adenocarcinoma of the

26:50

pancreas, because they arise in the duct,

26:53

they are ductal adenocarcinomas, one of

26:56

the first signs of a ductal adenocarcinoma:

26:59

dilation of the pancreatic duct.

27:02

Eventually, because it becomes obstructed,

27:05

you get atrophy of the portion of the

27:09

pancreas that is upstream in terms of the

27:11

direction of flow of pancreatic juices.

27:14

So this is not an adenocarcinoma of the pancreas.

27:18

This is another case of lymphoma, in this

27:20

case involving the pancreatic head.

27:26

Here is also another case where there is smooth

27:30

retroperitoneal soft tissue surrounding the aorta.

27:34

And in this case, this is a diagnosis

27:36

of benign retroperitoneal fibrosis.

27:39

So something else to keep in mind when you

27:41

see homogeneous soft tissue nearly completely

27:44

surrounding or surrounding the aorta.

27:48

In these cases, you might also have, um,

27:51

medial displacement of ureters.

27:53

So if we had delayed imaging, the ureters

27:55

are often pulled in by this fibrotic process.

27:59

Um, if you can't tell if it's a little bumpier than

28:01

this, or you're trying to differentiate it from

28:04

lymphoma, a biopsy in these cases is also helpful.

28:10

And another case here of homogeneous soft

28:13

tissue, we're clearly involving, or at least—

28:17

next to the kidney.

28:19

And at first glance, this looks like another

28:21

lymphoma, and this would require a biopsy to

28:24

definitively make a diagnosis, because this in fact

28:27

was not like lymphoma, but a benign renal capsule.

28:32

Oncocytoma, which are very rare tumors that arise

28:34

from the capsule of the, of the kidney,

28:38

um, tend to be benign as in this case.

28:42

But again, it can mimic lymphoma.

28:47

Water attenuation lesions in the retroperitoneum

28:50

tend to be benign, um, unless they are

28:54

determined to be completely necrotic.

28:57

In this case, we have a water attenuation

28:59

lesion with a barely perceptible wall.

29:01

There may be a few little septations within it.

29:04

It doesn't seem to be associated with any particular

29:07

organ, and it looks really non-aggressive.

29:11

In this case, we can be pretty sure.

29:13

This is a lymphangioma, which is just

29:16

a, uh, benign lymphatic malformation.

29:20

They can be very small, they can be much larger

29:22

than this, but when there are water attenuation

29:24

like this, you can be pretty confident, at least in

29:27

saying that it's not gonna be something aggressive.

29:30

Here's another lesion.

29:32

Looks very similar.

29:33

Water attenuation in the retroperitoneum.

29:37

And again, this was another lymphangioma.

29:42

Now, in this case, we have a lot of water attenuation.

29:46

It's in the retroperitoneum, but it's completely

29:48

surrounding the pancreas, and I don't think anybody's

29:50

really gonna have difficulty making a diagnosis of

29:53

pancreatitis in this case, but I'm just throwing it

29:56

in for completeness' sake, just to show you that again.

30:00

Retroperitoneal processes

30:01

with water tend to be benign.

30:04

Although pancreatitis can be aggressive,

30:07

it is still a benign process.

30:12

And again, water attenuation lesions.

30:14

We have one that's associated with the pancreatic

30:17

head, one that's associated with the pancreatic

30:19

tail, and this is, again, sequela, in this

30:23

case, of pancreatitis or pancreatic pseudocysts.

30:27

So another water attenuation lesion

30:29

in the retroperitoneum that is benign.

30:34

All right, well, what if you really

30:35

can't make a specific diagnosis?

30:38

Can you at least suggest if a lesion is more

30:40

likely to be malignant and therefore more worrisome

30:43

versus something that's more likely to be benign?

30:46

There are some guiding principles

30:47

that I like to think about.

30:49

They're not foolproof, but things that may

30:52

make you think that something is malignant.

30:55

Are that, you know, the patient may be

30:57

symptomatic, so they may have constitutional

30:59

symptoms like they've had weight loss or fever.

31:03

Or they have pain.

31:05

Um, if a mass has very irregular margins

31:07

or is very infiltrative, it's probably more

31:10

likely to be malignant if there's necrosis.

31:14

Again, unless the lesion is a very vascular,

31:17

benign lesion, necrosis is usually in malignancy.

31:21

And if it's really larger, I mean, larger lesions

31:24

tend to be malignant than smaller lesions.

31:27

And the only thing I can really say otherwise

31:29

is that if it has none of those features,

31:30

it's probably more likely to be benign and.

31:34

Lesions that have not been treated, if they have

31:36

calcification, tend more likely to be benign.

31:40

So let's go through a few and see if

31:41

we could determine whether we think

31:42

something's benign or malignant.

31:45

So we have here a large mass.

31:48

It's very large.

31:49

There are areas of necrosis in it.

31:52

It was not possible to definitively decide

31:54

what organ it was arising from other than it.

31:57

It was just pushing on the kidney here, so not arising

32:00

from the kidney, and it was definitely retroperitoneal

32:03

based on the way it moved bowel and so forth.

32:06

In this case, we can lean malignant

32:08

because of the necrosis, and this

32:11

was a malignant fibrous histiocytoma.

32:13

I can't tell you that I would know that that's what

32:16

this was just based on the, any other feature of it.

32:20

But I would lean malignant because of its

32:22

large size and because there's necrosis.

32:26

How about this one?

32:29

There is some central necrosis.

32:30

In this case it was pushing on the

32:32

kidney, had engulfed the adrenal gland.

32:35

So we're already thinking probably malignant.

32:38

Is it primary malignancy from the

32:40

adrenal, or is this a metastasis?

32:42

Oh, again, history in this case would be

32:44

helpful 'cause this is another metastatic

32:46

lung carcinoma to the adrenal gland.

32:51

In this case, we have a very

32:53

vascular and very infiltrative mass.

32:57

It is involving the left, excuse me, the right kidney.

33:00

It looks like it might be within some

33:03

vessels within the kidney, and then

33:04

there's a large component that's exophytic.

33:07

It is again retroperitoneal.

33:09

There's a lot of necrosis, so we know this is

33:12

most likely malignant, and this is just again,

33:15

turned out to be another renal cell carcinoma.

33:18

In this case, one of the things that we need

33:20

to be concerned about, just because of its

33:22

large size and the way it's infiltrating

33:24

anteriorly, is whether there, there is actually

33:27

involvement of the liver in this case, or

33:29

whether this is just contiguous with the liver.

33:32

So will this just peel off the liver,

33:34

or will there have to be some sort of—

33:36

um, liver resection in order to

33:38

definitively get rid of this tumor?

33:41

And that's something that can be very difficult

33:43

to tell, but it's very important that this

33:45

is mentioned in a report—that you can't tell

33:48

whether it's just next to or invading the liver,

33:51

because then the urologist might have a liver

33:55

surgeon on hand to help with surgery if need be.

34:00

How about this one?

34:02

It's a very large mass.

34:04

There are very large areas of soft tissue,

34:07

but there are also fatty components, so

34:10

this is similar to one we've already seen.

34:12

I don't think we have any doubt that

34:13

this is a malignant liposarcoma and

34:17

not a benign lipoma or lipomatosis.

34:23

How about this case in contradistinction?

34:25

One of the kidneys has been resected.

34:30

We have this other kidney here surrounded

34:32

by this relatively bland-looking fat.

34:34

There is mass effect, but

34:36

again, relatively bland-looking.

34:39

And this is lipomatosis,

34:41

not a malignant liposarcoma.

34:47

And in this case—

34:51

are we leaning benign or malignant?

34:52

I will tell you this little

34:53

mass here was not symptomatic.

34:56

It has very smooth borders, so not irregular.

35:00

There's no necrosis.

35:01

It's not very large, so we're leaning benign.

35:04

In this case, this was a benign schwannoma.

35:10

All right, we do have some more time here, so

35:13

I have some more cases that we can go through.

35:17

So here's a first—whether this is

35:20

retroperitoneal or not retroperitoneal.

35:23

Well, again, we're pushing the ascending colon forward,

35:27

and we've got areas of necrosis, so it's large.

35:30

So we're thinking malignancy, and this case was a

35:34

dedifferentiated liposarcoma.

35:40

We have this case.

35:42

Is it retroperitoneal?

35:44

Well, it is behind the pancreatic head, so we're

35:47

suspecting that it is indeed retroperitoneal.

35:50

There are areas of necrosis.

35:53

In fact, it's very heterogeneously enhancing.

35:56

Some areas are not enhancing well at all.

35:58

So we are leaning retroperitoneal.

36:02

What would its organ of origin be?

36:05

Well, we've got two possibilities here.

36:07

It looks like there might be a beak sign,

36:09

at least partially with the kidney, but

36:11

then not so much in the other area here.

36:14

Here it looks more like it's

36:15

compressing and not really beaking.

36:18

What else is it

36:19

compressing or beaking with? Well, it's very

36:22

intimately associated with the inferior vena

36:24

cava, which we can see here as this little

36:26

sliver and kind of being obliterated here.

36:29

Here is unopacified blood in the

36:31

IVC here, so it's very intimately

36:33

associated with the inferior vena cava.

36:36

So we need to at least consider—and what

36:40

turned out to be in this case, an IVC sarcoma.

36:43

So another case of that.

36:48

Here's a lesion.

36:49

It's got water attenuation mostly.

36:52

This was—I give you a date here

36:54

because I'm gonna give you a comparison.

36:56

It's pushing the—

36:58

colon forward.

36:59

So it is indeed retroperitoneal.

37:01

There is a plane with the kidney here,

37:04

so it's not arising from the kidney.

37:07

It's got some enhancing septa and a perceptible wall.

37:11

So even though it's more like it is water

37:13

attenuation, it's like this is not really

37:16

typical of our, our usual, um, lymphangioma.

37:21

There's some inflammatory change

37:23

here though too, around the kidney.

37:26

Well, let me show you what the patient looked

37:28

like two weeks—about two weeks previous.

37:31

So here, this is way more typical for our

37:33

usual benign lymphangioma, water attenuation.

37:37

You really don't perceive a wall,

37:39

you don't perceive any septa, and what

37:42

had happened—this is his a lymphoma.

37:45

The patient came back now symptomatic with

37:47

a fever, and this had become infected.

37:51

By some way, shape, or form.

37:53

Not sure how these become infected, but he somehow

37:56

became septic and this became infected, which

37:59

makes it look a little bit more aggressive, a

38:01

little less like our usual benign lymphangioma.

38:04

But that's because it's a—because of

38:06

infection, not because of malignancy.

38:09

So this was treated with antibiotics, and you

38:11

can drain these if need be as well, or at

38:14

least, um, sample them for the appropriate—

38:17

bug that might be growing there,

38:19

and the patient did recover.

38:23

How about this lesion?

38:24

It's sitting on top of the psoas muscle, so

38:27

we're pretty sure that it is retroperitoneal.

38:29

It's also pushing some of the bowel loops forward.

38:33

It's pushing gonadal vessels and some

38:35

and mesenteric vessels forward.

38:39

It has necrosis.

38:40

So we're thinking it's, uh, malignant.

38:43

But then again, we do have to keep in mind

38:46

that very vascular tumors can have necrosis.

38:49

And I've shown you a couple examples already,

38:52

and this was another paraganglioma.

38:58

Here's another patient, a relatively large mass.

39:03

We can't discern the right adrenal gland.

39:05

It's in the engulfed organ sign.

39:07

Again, there's no beak with the kidney.

39:09

So again, we're thinking adrenal in origin.

39:13

There are some small areas of low attenuation.

39:16

So what do we all wanna do

39:17

when we see an adrenal lesion?

39:19

This patient had no history of any other

39:21

carcinoma, so we're not suspecting metastases.

39:24

We have our usual adrenal

39:26

protocol here with a non-contrast.

39:29

We have, uh, arterial, portal venous, and

39:32

delayed images, so we want to get

39:36

attenuation values on it, so we do that.

39:40

And we have, uh, 45 Hounsfield units

39:43

before we gave contrast material.

39:45

So certainly not a typical of an adenoma.

39:49

We have 67 Hounsfield units on the initial portal

39:53

phase, and it didn't wash out on the delayed phase.

39:56

So we already know this is not an

39:57

adenoma, but I want to caution you.

40:01

When lesions are larger than three centimeters, using

40:04

adrenal washout protocols are really not as accurate.

40:08

Plus, there's also something we need to keep in mind.

40:10

When adrenal lesions are more than three centimeters,

40:14

it's already the cutoff for when we should start

40:16

thinking about adrenocortical carcinomas.

40:19

And this lesion is very heterogeneous, with

40:21

areas that are probably not enhancing as well.

40:24

And this was indeed an adrenocortical carcinoma.

40:28

So you're not going to get accurate

40:30

measurements with washout on anything

40:32

that's more than three centimeters.

40:34

You've gotta think about adrenocortical carcinoma.

40:39

Here's another case.

40:40

This lesion has somewhat of what

40:42

turned out to be calcifications.

40:44

They could be areas of intense enhancement.

40:47

Having a non-contrast image would be helpful

40:49

to know that these are indeed calcifications.

40:53

Having delayed images would also help you

40:54

know that these are calcifications 'cause they

40:56

wouldn't change when we see calcifications.

40:59

I said, well, you gotta think

41:00

about something being benign.

41:03

This is really big.

41:05

It's engulfed the adrenal.

41:07

We can't find the adrenal.

41:08

It looks infiltrative into the adjacent liver.

41:11

There's some parenchymal changes in the adjacent

41:13

liver that make you wonder if it's in, um—

41:16

invading.

41:18

It's got a lot of mass effect here, pushing

41:20

this kidney down, pushing the IVC, but doesn't

41:23

look like the, the IVC doesn't look irregular

41:26

at all, so I don't think this is an IVC sarcoma.

41:30

Again, any adrenal mass that's greater

41:33

than three centimeters has to be

41:34

considered potentially malignant.

41:36

In this case, the lung bases also helped,

41:39

'cause there were clearly

41:40

multiple soft tissue nodules.

41:42

Sorry, my arrows are in the wrong place.

41:44

Multiple soft tissue nodules that enhanced

41:46

very similarly to the primary lesion.

41:49

And this was metastatic adrenocortical carcinoma.

41:55

How about this case again—why are

41:58

we leaning benign and malignant?

42:00

So we wanna know, was this symptomatic?

42:02

I wanna say yes.

42:03

I'm not gonna tell you what the symptoms were, but

42:05

the patient did present because they didn't feel well.

42:08

Does it have irregular margins?

42:11

Well, mostly smooth.

42:13

Um, maybe a little bit irregular.

42:15

The internal margins look a little irregular.

42:18

Is there necrosis?

42:20

Well, certainly there is area of non-enhancement

42:24

centrally, so that could mean necrosis.

42:27

Is it large?

42:28

I guess it depends on what

42:29

your definition of large is.

42:30

It's certainly more than three centimeters.

42:33

So it's relatively large.

42:35

All right, now I'm gonna tell

42:36

you what the symptoms were.

42:38

This patient came in with pain and fever and

42:42

some dysuria, and if we look carefully in the

42:45

parenchyma of the kidney next to it, we can

42:47

see some areas that are not enhancing as well.

42:50

And this turned out to be a pararenal abscess.

42:53

So this is not necrosis per se, but pus in here.

42:57

And this would be treated very differently

42:58

than if we thought this was a malignant

43:01

lesion arising from the kidney, either a

43:03

renal cell or a retroperitoneal sarcoma.

43:07

So again, the, the, the symptoms

43:09

certainly help in this case.

43:11

And if there's ever a doubt that this could be

43:12

something malignant, instead of putting a needle in

43:15

it—again, going through an appropriate track that

43:18

a surgeon wouldn't mind you approaching it from—

43:22

you can certainly get that.

43:23

It's not a malignant process when

43:26

you get frank pus from your sample.

43:31

In this case, are we leaning benign or malignant?

43:34

Well, the lesion is huge and there, so you,

43:37

you know, we're leaning malignant already.

43:39

There are certainly, uh—

43:43

Oops, sorry.

43:43

I didn't mean to do that yet.

43:44

Certainly this patient was symptomatic.

43:46

They presented with flank pain.

43:48

Um, it's very infiltrated, even though

43:50

the margins are relatively smooth.

43:52

And again, yeah, metastatic testicular

43:54

carcinoma in the appropriate clinical setting.

43:57

This person probably ignored a mass in their

44:00

testis, or it had one of those ones that burned

44:03

out, and we didn't know about it until they

44:05

presented with this very large infiltrative mass.

44:08

Again, this is not likely to be lymphoma because

44:11

it's untreated, because of the areas of necrosis.

44:16

And this is what it looked like after treatment.

44:18

Unfortunately, with these lesions,

44:20

they often don't completely regress.

44:22

They become more necrotic with treatment.

44:24

They do get smaller.

44:26

It's very hard to know whether there's

44:27

any viable tissue here at this point.

44:30

The patient also had a metastatic lesion in

44:32

his liver that had become necrotic as well.

44:38

How about this one?

44:40

In this case, we have a mass that seems to

44:42

be associated with the right psoas muscle.

44:45

There is necrosis, so we suspect

44:47

it's malignant, but there are a couple

44:49

of other clues we might wanna use here.

44:51

History again would be really important, but

44:53

if you don't have any history on

44:55

the patient, there is a surgical clip there.

44:58

We have a left kidney sitting

45:00

here, but where's the right kidney?

45:03

And this turned out to be

45:03

recurrent renal cell carcinoma.

45:06

Given the absence of the kidney and the

45:08

surgical clip, likely removed for that reason.

45:13

Now, if the kidney had been removed for benign reasons—

45:16

and there are a lot of benign reasons why a kidney

45:18

might be removed—then we would have to consider some

45:21

sort of retroperitoneal sarcoma, or even again, a

45:24

paraganglioma, given the necrosis, but a benign lesion.

45:32

And now here's one other case.

45:33

We have a lesion.

45:35

Here that's pushing the ascending colon forward.

45:39

So we know it's retroperitoneal.

45:41

It's certainly engulfing the right kidney.

45:44

And in this case, the history here is crucial,

45:47

'cause this turned out to be a very large

45:49

hematoma, and this patient had been in an automobile

45:52

accident, and again, that's not a history that you

45:55

wouldn't have—knowing the patient had a trauma.

45:58

You're not going to think that this is a malignancy.

46:01

There is a reason for this patient

46:03

to have had a renal hematoma.

46:05

In patients that have spontaneous renal or perirenal

46:08

hematomas, then you do need to be concerned that there

46:12

is an underlying malignancy that ruptured or bled.

46:15

So in those cases, it's very

46:17

different than a case of trauma.

46:22

So hopefully you've gained a few clues that'll help

46:24

you decide whether a mass is retroperitoneal or not.

46:27

Um, again, based on its location, what's—

46:30

what is it doing to surrounding structures?

46:32

Uh, I talked a little bit about beak or claw signs,

46:36

uh, the embedded organ or phantom organ signs.

46:39

Um, we talked about, uh, fat-

46:42

containing lesions, calcium, necrosis.

46:45

Water attenuation lesions, soft tissue lesions.

46:48

So those should help you, give you a clue as well.

46:51

And when all else fails, other than the paraganglioma,

46:54

which I showed multiple examples of, you can

46:57

usually lean benign or malignant pretty easily.

47:00

And anything that you can do to get history on

47:03

a patient, to find out whatever symptoms they might

47:05

be having, any previous imaging you might have,

47:09

which would let you know whether the lesion has

47:10

grown or stayed stable, all of those things are

47:13

gonna be clues that'll help you decide those things.

47:17

And now I will see if there is—

47:20

or other questions?

47:21

I think there are many other

47:22

questions that I haven't answered yet.

47:25

So, um, let's see.

47:26

We have one here that says there has been teaching

47:28

that true retroperitoneal lipomas are rare,

47:31

and that even in the absence of soft tissue

47:32

nodules, you should be hesitant to call them.

47:34

Do I agree with that?

47:38

I agree with you that retroperitoneal liposarcomas,

47:41

or even well-differentiated liposarcomas,

47:44

are really way, way more common, which is why I had

47:48

also mentioned that pathology can be very helpful.

47:51

Um, you do—when you wanna target a

47:54

fatty lesion in the retroperitoneum,

47:56

you wanna target the areas that

47:58

look the least bland fat.

48:00

So look for the soft tissue nodules.

48:02

Look for areas that have septa

48:05

or other streaks of soft tissue.

48:07

Those are the areas that you wanna sample,

48:10

and you probably wanna sample more than one area,

48:12

but there are genetic testing that can be done on

48:14

these lesions that do really help you differentiate

48:18

lipomas from the spectrum of liposarcoma.

48:21

So if you're ever unsure,

48:24

then you can say it's very

48:25

bland, it's very homogeneous.

48:27

I'm leaning lipoma versus well-

48:29

differentiated liposarcoma.

48:32

But a biopsy might be helpful.

48:34

The patient might still end up getting

48:36

something that is that large removed anyway,

48:39

because even benign lesions, when they're

48:41

large and push on things, can cause trouble.

48:45

When should we send a patient to biopsy if we have

48:47

a fat mass in the kidney and not call it—

48:51

to not call it an AML. I think if you're very

48:54

confident that you can see the origin from the

48:57

kidney because there's a beak sign, because

48:59

there's a divot, and you can be confident

49:03

that it's an AML, I would be okay with that.

49:05

Just calling it an AML. Um, if you're hesitant,

49:09

because of its large size or because it has some

49:12

features that are atypical, you really can't find

49:14

that feeding vessel or that divot that lets you

49:16

know that it's coming from the kidney, then you're

49:18

probably fine to go ahead and do a biopsy on it.

49:22

Um, again, if you have any previous imaging, it

49:25

might be helpful, even previous imaging that it's not

49:28

mentioned on, because maybe somebody didn't notice it.

49:31

For example, I am a huge

49:33

proponent of looking at chest CT,

49:35

'cause you got the bottom—you got the top

49:36

of the abdomen at the bottom of the chest.

49:39

Any kind of spine imaging, you often

49:41

have scouts, and people may have neglected

49:43

to look at a scout on a spine

49:46

series—either thoracic or lumbar spine—

49:50

that you might see some of the retroperitoneum

49:52

and be able to determine, well, gee,

49:54

this lesion was there three years ago.

49:56

So even though I'm not sure it's an AML, it

49:59

looks the same, so I'm gonna be more confident.

50:02

Um, any kind of nuclear medicine study that

50:05

they might have done, a SPECT CT with—

50:08

look at that.

50:10

Um, so there are other clues that you can use.

50:13

Even a pelvic MRI or a pelvic CT might

50:16

have a scout that is helpful, or might have

50:19

gone a little higher than you'd expect.

50:21

So those can be really helpful.

50:23

Um, relapse after surgery is

50:26

very common in these patients.

50:28

I'm assuming you're talking about retroperitoneal

50:30

liposarcomas or retroperitoneal sarcoma patients.

50:33

What time would be good for follow-up

50:35

and detect the tumor before it reappears?

50:37

And what imaging study would be the best?

50:39

That's a really hard question.

50:41

Um, the more, uh, different, the more

50:45

aggressive, they probably relapse sooner.

50:49

I, I, I would be lying if I told you I had an exact

50:52

number in my head, like three months or six months.

50:56

I think things you need to be really careful about,

50:59

is with these liposarcomas, is that sometimes

51:02

the fat that comes back is very bland-looking,

51:06

so you've gotta be very careful to compare.

51:09

You're old, you're sort of your immediate post-op.

51:13

Where they've got the post-op changes has been,

51:16

taken care of, so there's not a lot of hemorrhage,

51:18

or, or fluid, but they haven't recurred yet.

51:20

So it may be helpful to have a baseline of,

51:22

what they look like after surgery, so you know,

51:25

what's been resected, what's still left there.

51:27

And you need to very carefully look at the fat.

51:30

Is there extra fat in any location?

51:32

Is there now fat that otherwise looks benign but is,

51:35

pushing on something, so fat that causes mass effect?

51:39

That wasn't doing that before is a,

51:42

is a clue, a subtle clue to a relapse.

51:45

Um, and I guess it also depends on when,

51:48

you get the pathology back, how aggressive,

51:50

the grading on pathology would give you,

51:52

a clue if you have to look more quickly.

51:55

Certainly any patient that becomes symptomatic that,

51:57

wasn't, might need to be scanned sooner than later.

52:01

In terms of which.

52:02

Studies to use, whether you wanna say,

52:04

do an MRI or a CT, I think you should,

52:07

stick with what you have as the baseline.

52:09

So if you've been doing MRIs on that patient,

52:12

it's probably easier to continue to do MRI.

52:14

If you've been doing CT, it's probably easier to,

52:17

do CT and I have seen plenty of cases where we've,

52:20

determined that there's been a relapse on CT.

52:23

So I don't think that MRI is necessarily better.

52:27

Um, can we.

52:31

Uh, can we safely biopsy,

52:33

all unknown retroperitoneal masses?

52:35

Are there contraindications and do,

52:37

not touch retroperitoneal lesions?

52:40

Um, I think if you have a window that you're,

52:42

not crossing any vital structures, it's,

52:45

probably safe to biopsy almost anything.

52:48

That being said, I would talk to a surgeon before,

52:52

I stuck a needle in something that I really thought,

52:55

was a sarcoma, because you don't want to contaminate,

52:59

a tissue plane that they are not going to use.

53:02

To get to an organ or to get attached to the mass.

53:05

This is also true in any of your MSK cases where,

53:08

you've got, say, an anterior compartment thigh lesion.

53:11

You don't wanna biopsy it through the,

53:13

posterior compartment 'cause a surgeon is not,

53:15

going to resect the posterior compartment.

53:18

So I would talk.

53:19

Very closely with the surgeon, the treating,

53:21

the treating surgeon for a lesion before,

53:24

you stuck a needle in it, just to make sure,

53:25

you're gonna go through a path that's okay.

53:28

Um, clearly any lesion that's very vascular,

53:31

you've gotta be aware that you could have bleeding.

53:33

But that would be a con, that would,

53:34

be a, a caution to any biopsy.

53:36

I. So I think you can probably safely biopsy,

53:40

most. The other retroperitoneal mass that,

53:43

people are concerned about would be an,

53:45

adrenal or an extra-adrenal pheochromocytoma.

53:49

Hopefully, if you are suspecting that before you,

53:51

do a biopsy, you would have urine metanephrines.

53:55

Another clue that that might be what you're,

53:56

dealing with, so that you can appropriately,

53:59

medicate the patient for any untoward release,

54:02

of hormones that might happen during a biopsy.

54:06

Um, how to differentiate areas of water cystic,

54:09

component from necrosis inside a mass. Difficult.

54:12

I agree.

54:14

Um,

54:17

I think you wanna look at some of the other,

54:18

characteristics of the lesion as well to,

54:21

help you decide if it's just purely water,

54:24

uh, or not. Sometimes, um, the, whether the,

54:26

inner margins are also irregular-looking.

54:29

Is it infiltrative, that sort of thing.

54:32

Um.

54:33

Clearly when you're doing a biopsy and you,

54:35

want to get a definitive diagnosis, you wanna,

54:37

avoid the areas that are necrotic and go for,

54:39

the areas that are enhancing or soft tissue.

54:43

So that could be helpful.

54:45

What are common sites for abdominal ganglioma?

54:48

The only ones I've ever seen,

54:49

are the ones I've shown you.

54:50

So they tend to be retroperitoneal,

54:52

like I've shown you those.

54:53

Um, do VAs vascular malformations, can,

54:57

desmoid occur in a retroperitoneal?

54:59

I've never seen a retroperitoneal desmoid.

55:02

That doesn't mean that it doesn't happen.

55:04

Um, but I've not seen one. How to differentiate,

55:07

oncocytoma from renal cell carcinoma.

55:11

We've been trying to do that forever.

55:13

There are probably some clues you can use.

55:15

There's that stellate central scar,

55:17

but the enhancement pattern of renal cell

55:19

carcinomas and oncocytoma are very similar.

55:22

If you think something is an oncocytoma just,

55:25

based on your gestalt and the sort of central,

55:28

scar thing, then doing a biopsy honestly and,

55:32

getting OncoCyte is probably gonna lean you,

55:35

toward an oncocytoma versus a renal cell.

55:39

How can we differentiate liposarcoma,

55:41

from adrenal myelolipoma and CT?

55:43

Some of that has to do with size.

55:46

Um, the, the smaller lesions that you can clearly see,

55:50

splaying the adrenal, or that are embedded in a limb,

55:54

of the adrenal are more likely gonna be myelolipomas.

55:57

The more infiltrative ones, like that really,

56:00

large one I showed you that came out, we,

56:02

really could not tell that that wasn't just,

56:04

like a well-encapsulated liposarcoma.

56:08

Have I encountered a hydatid,

56:09

cyst in the retroperitoneum?

56:11

I have not personally encountered one in,

56:13

the retroperitoneum, but I have also not,

56:16

encountered that many hydatid cysts in my career.

56:18

'Cause they're just not that common where I,

56:20

practice. I. Then the, I think I answered this,

56:24

one already, but can we always localize all,

56:26

retroperitoneal masses and determine the origin?

56:28

I think we've determined that, no,

56:30

it is not possible to always do that.

56:33

We always just do our best.

56:34

We use all the clues that we can come up with and,

56:37

do our best to try to at least give a reasonable,

56:40

differential, or at least clue in the patient and,

56:43

their referring physician that what you're dealing,

56:46

with may be malignant and that you wanna be a,

56:48

little bit more aggressive about working it up.

56:51

So I think that answers all of the questions on there.

56:54

Um, I don't have all the answers.

56:56

I'm sorry I don't have all the answers to everything.

56:59

Um, I try to use my, um, experience as best I can and,

57:03

um, try to get it right as often as I possibly can.

57:07

And, um.

57:08

If anybody has any further questions, or you,

57:11

know, really any other questions for me,

57:14

um, FRI online has my, um, email address.

57:18

I should have typed it on my last,

57:19

slide, but it's my last name.

57:22

Dot my first name, so Baumgarten,

57:25

dot debra@mayo.edu.

57:30

And thanks so much for your attention.

57:32

You've been excellent and interactive.

57:35

Thank you so much.

57:36

As you bring our time together to a close,

57:38

I want to thank Dr. Baumgarten for,

57:40

this lecture and thanks to all for,

57:41

participating in our noon conference series.

57:43

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57:45

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58:04

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58:06

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58:08

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58:11

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58:13

Lee from Boston Children's Hospital.

58:15

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58:18

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58:21

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58:23

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