0:02

Hello, and welcome to Noon

0:03

Conferences hosted by MRI Online.

0:05

In response to changes happening around the world

0:07

right now, and the shutting down of in-person

0:09

events, we've decided to provide free daily

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noon conferences to all radiologists worldwide.

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Today, we're joined by Dr. Emily Webb.

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Emily Webb, M.D., is a professor of clinical radiology

0:19

in the Department of Radiology and Biomedical Imaging

0:22

at the University of California, San Francisco.

0:25

She's the Director of Medical Student Education in the

0:27

Haile T. Debas Academy Chair and Radiology ED Education.

0:32

Quick reminder, there will be time at the

0:33

end of the hour for a Q and A session.

0:35

Please use the Q and A feature to ask your questions,

0:37

and we'll get to as many as we can before time's up.

0:40

That being said, thank you so

0:41

much for joining us today, Dr. Webb.

0:43

20 00:00:43,380 --> 00:00:44,790 You can unmute now, and I will

0:44

let you take it from here.

0:46

Okay, uh, welcome, uh, to

0:49

this virtual noon conference.

0:52

Um, happy to be here.

0:53

I'm gonna be talking about, um, atypical

0:57

pancreatic masses today, and, uh, let me get.

1:03

My little move ahead button.

1:05

Um, what I really mean by that are pretty much, you

1:10

know, all the pancreatic masses other than pancreatic

1:13

adenocarcinoma, which we think of as sort of being

1:15

our run-of-the-mill, most common pancreatic mass.

1:18

So, I'm gonna divide it into sections.

1:20

I'm gonna start by talking about cystic pancreatic

1:23

masses, which are always a cause for confusion.

1:26

Um, I'm gonna start with the,

1:27

what I call the big four of those.

1:30

Then, I'm gonna talk a little bit about just a

1:32

few other cystic masses to round things out.

1:35

Um, a little bit about neuroendocrine

1:37

tumors, and then lastly, a few important

1:41

mimics, uh, that aren't actually pancreatic

1:43

masses, but can be confused for one.

1:46

So, that is our list of topics for the day, and I'm

1:51

gonna start with the big four cystic pancreatic.

1:56

Now, what are these big four that I'm talking about?

1:58

The first would be pseudocyst.

2:01

Second, a serous cystic neoplasm.

2:04

This is the old, uh, so-called microcystic,

2:08

um, uh, adenoma of the pancreas.

2:11

A name I kind of like a little bit better because

2:13

it, uh, describes the appearance, uh, the mucinous

2:18

cystic neoplasm, the old macrocystic adenoma.

2:23

And then lastly, intraductal

2:25

papillary mucinous neoplasm, or IPMN.

2:28

So, these are the four cystic things we're

2:30

gonna concentrate on in this section.

2:33

Now, what are our goals for this portion,

2:35

um, of the talk? We're gonna review the

2:37

different imaging features of these pancreatic

2:39

masses with an eye towards differentiation.

2:42

Can we tell them apart from each other?

2:46

And, uh, perhaps more importantly, can we

2:49

differentiate which ones are benign from which ones

2:53

are malignant, and then we'll talk about management

2:56

because that's where a lot of the, um, confusion

2:59

lies in talking about cystic pancreatic lesions.

3:02

So, first, pancreatic pseudocysts.

3:06

Now, it's very helpful if you're trying to

3:08

make a diagnosis of a pancreatic pseudocyst,

3:10

uh, if you have some history of pancreatitis or

3:13

trauma or surgery, or something that would give a good

3:16

reason, uh, for that patient to have a pseudocyst.

3:21

Beyond that, when we look at just the morphology

3:24

of what we're looking at, uh, pancreatic

3:26

pseudocysts are more commonly eccentric or

3:29

even exophytic compared to the other types

3:32

of cystic neoplasms we're talking about.

3:35

They can be multilocular, but they are often unilocular.

3:41

But the truth is, if you don't have any, uh,

3:44

concomitant imaging evidence of pancreatitis,

3:47

or you don't have, you know, sequential scans

3:49

where you're seeing evidence of pseudocyst

3:52

evolution, it can be impossible to differentiate

3:55

these from cystic pancreatic neoplasms.

3:58

Here's some examples of what I'm talking about.

4:00

So, here's sort of like your perfect case, um, where

4:03

you have evidence of pancreatitis on a previous

4:07

scan, uh, with all of this fluid and fat stranding

4:09

around the pancreas, and then on a subsequent

4:12

scan we see that this eccentric, unilocular, exophytic

4:18

looking cyst has evolved, wasn't there before.

4:22

This is classic for a pseudocyst.

4:27

Oops.

4:27

End show.

4:28

Um, here on MR, if you happen to have

4:30

an MR, there are some other signs we can

4:32

look for that can sometimes be helpful.

4:34

This is not something you hear a lot about,

4:36

but it's something I look for when I'm trying

4:38

to decide if something might be a pseudocyst.

4:40

If you see on T2 any, um, layering of internal

4:44

debris, uh, within a cystic lesion, that is

4:48

a sign that is suggestive of pseudocyst formation.

4:50

So, look for that.

4:52

Uh, if you are looking at an MR. Now, moving on

4:56

to the second one, the serous cystic neoplasm.

5:00

So, these are benign lesions, so we would

5:03

like to be able to confidently recognize

5:05

them because, uh, they're benign, and we

5:08

don't have to really do anything about them.

5:10

They tend to occur in older women.

5:12

But I want you to note the age range here, 60 to 70.

5:17

Occur more commonly in the pancreatic head.

5:20

And as I am telling you that, I'm showing you an

5:22

example in the pancreatic tail, so obviously they can

5:25

occur anywhere, and they are comprised of multiple

5:30

small cysts.

5:32

I think of these as almost having, um,

5:34

a bit of a, a honeycomb appearance.

5:36

Lots of little cysts clustered together.

5:39

Now, they can sometimes have a central scar, and

5:42

that central scar can sometimes be calcified.

5:47

And here is an example of that.

5:48

So, this cystic neoplasm really has it all.

5:52

It's like a textbook classic.

5:54

It has that microcystic morphology.

5:57

It has a, what's called a microlobulated

6:01

contour, where if you sort of follow around

6:03

the margin of this thing, lobulated,

6:05

lobulated, that's great for these lesions as well.

6:09

And then we actually do see

6:12

calcified central scar here.

6:13

Now, usually when I show this image, I'm

6:15

like, yeah, this is great if you see it.

6:17

But you never see them looking exactly

6:20

like this and having all these features.

6:22

And I swear, for the first time in my career,

6:25

yesterday, I saw one that looked exactly like this.

6:27

Microcystic, microlobulated

6:30

contour, central calcified scar.

6:32

It was very exciting.

6:34

Uh, but this is perfect if you

6:36

see a serous cystic neoplasm.

6:39

Now, the mucinous cystic neoplasms look a bit similar,

6:43

uh, to the serous, but a little bit different.

6:45

So, what we're looking for here, um,

6:48

is, uh, larger cysts.

6:51

So, the old one, the serous, were the

6:52

microcystic, these were the macrocystic.

6:55

So, these tend to be comprised of fewer, larger

6:59

cysts as opposed to that more honeycomb appearance.

7:02

Now, we wanna be able to recognize these

7:04

mucinous lesions, uh, as mucinous because

7:08

these have malignant potential and can

7:11

degenerate to mucinous cystadenocarcinoma.

7:14

Um, so we're looking for these features

7:17

to be able to identify them as these

7:19

potentially malignant mucinous lesions.

7:22

Now, I said that those microcystic

7:24

ones tended to occur in older women.

7:26

These tend to occur in younger women.

7:28

But again, look at the age range here, 50 to 60.

7:32

The older women age range was 60 to 70.

7:35

So, you can see that there's

7:36

like a fair amount of overlap.

7:37

The demographics aren't really, uh, that helpful.

7:41

And these shouldn't have that central scar.

7:45

Uh, but these can sometimes calcify.

7:47

When they calcify, they tend to get a thicker wall

7:50

peripherally, and that wall can sometimes calcify,

7:54

giving you an appearance of rim calcification.

7:57

So, here's an example of another mucinous cystic neoplasm.

8:00

Bigger, a little different looking, but

8:02

overall, you've got a, a big cyst that has

8:05

some septations, and it looks multiloculated.

8:09

And we have this thick wall.

8:10

In some patients, you might see some

8:12

calcification within that thick wall.

8:14

This is a good look for a mucinous cystic neoplasm.

8:20

Now, IPMN, a little bit different than

8:22

the three we've talked about so far.

8:24

So, um, IPMNs are also mucinous lesions.

8:28

Obviously, mucinous is in the name.

8:30

Um, and these have malignant potential as well,

8:33

but they can exist along this whole spectrum from

8:36

adenoma all the way up to, um, invasive carcinoma.

8:40

You can almost sort of think about these

8:41

like some sort of pancreatic equivalent

8:43

of, like, colon polyps or something.

8:45

Now, these, uh, can have very different

8:47

appearances depending on where they are.

8:49

So, you can have main duct IPMNs that are just gonna

8:53

look like cystic dilation of the entire pancreatic

8:56

duct, or they can involve the side branch.

8:59

And when they involve the side branch, they can

9:01

look a little bit more like a focal cystic lesion.

9:06

If you've got one of these main duct

9:07

ones and you do an ERCP, you can see, like,

9:10

this mucin sort of bulging out the ampulla.

9:12

And that's supposed to be a real, uh, classic finding.

9:15

This is a main duct IPMN, where it really

9:18

just looks like cystic dilation of the duct.

9:20

Kind of hard in some cases to differentiate from

9:23

other causes of just pancreatic ductal dilation.

9:26

But the ones we're most concerned about in

9:28

this differential where we're trying to debate,

9:30

is it a pseudocyst, is it a serous lesion,

9:33

is it a mucinous cystic lesion,

9:36

are the side branch IPMNs, because

9:39

those are more focal and more discrete.

9:42

Here, an example of one, I think

9:44

I've got a little marker there.

9:47

Um, this is the first time I've said

9:49

that these are more common in men.

9:51

So, these are a little bit more common

9:52

in men than the other cystic lesions.

9:55

Uh, the cysts that we look for can be

9:57

single, just like, you know, the kind

9:59

of TSTC-looking lesion in the pancreas.

10:02

So, just a small cyst, or it can have this

10:05

appearance where there's multiple cysts.

10:08

And I always think of IPMN as looking like

10:11

cysts next to cysts, as opposed to cysts within cysts.

10:15

So, if you have got, like, the single sort of

10:18

ocular lesion that has septations within it

10:20

or cysts within it, then I'm thinking more of

10:23

the, um, serous or mucinous cystic neoplasms.

10:26

But if you have a collection of cysts that just look

10:29

like they're clustered next to each other, more like

10:31

a bunch of grapes or something, then I think of IPMN.

10:36

Now, these, of course, are arising in the side branches

10:40

of the pancreatic duct, so you should theoretically be

10:43

able to see some communication to the pancreatic duct

10:47

because they do communicate with the pancreatic duct.

10:49

Sometimes it can be harder than others.

10:52

Um, but that's something we look

10:53

for to help confirm the diagnosis.

10:55

And sometimes you'll actually see that cystic

10:57

dilation spilling out from the side branch into

11:01

the adjacent main duct and involving the main

11:03

duct, which tends to have a worse prognosis

11:05

in terms of, uh, degeneration to malignancy.

11:10

Here, another example where we actually can,

11:12

um, appreciate the communication between

11:15

the cystic lesion and the main duct.

11:18

There it is.

11:18

Here's the sort of bulk of the cyst, and

11:20

then communicating into the main duct

11:22

here, which looks a little bit dilated.

11:28

Okay, so we've gone over all the features.

11:30

Again, what are the goals?

11:31

Why are we, like, trying to look at all this stuff?

11:34

Number one.

11:35

We really wanna be able to differentiate

11:37

benign from, frankly, malignant lesions.

11:40

I mean, that's, uh, sort of our

11:42

goal in a, a lot of radiology.

11:44

But the sort of extra step here is we

11:47

would like to be able to differentiate the

11:51

benign from potentially malignant lesions,

11:53

which essentially are the mucinous lesions.

11:55

We wanna be able to identify the mucinous cystic

11:58

neoplasms and the IPMNs and recognize them as

12:00

different from the serous lesions or the pseudos

12:04

so that we can watch them and, uh, make sure

12:08

that they don't degenerate into malignancy.

12:10

So, that would be the perfect world.

12:13

So, let's talk about the first step first.

12:16

So, um, identifying whether

12:18

these are malignant or benign.

12:21

So, what about features that would suggest benignity?

12:26

So.

12:26

If you look up what features, uh, you can confidently

12:31

say indicate that a pancreatic cyst is benign,

12:35

what you'll see is going to sound very familiar.

12:38

They're gonna talk about the presence of a

12:39

central scar that may or may not be calcified.

12:43

That's supposed to be a hundred percent specific

12:45

in the literature for benignity, or a combination

12:51

of that microcystic morphology, that honeycomb

12:54

appearance, and a microlobulated contour.

12:57

So, obviously, all they're describing here

12:59

are the features of a serous cystadenoma.

13:04

Because we know those are benign.

13:06

And if you have these absolute textbook

13:09

classic features that are supposed to be a

13:11

hundred percent specific, you can be pretty

13:13

confident that that is a benign serous lesion.

13:18

Now, as I said before, you don't see, like, all of

13:22

these features together that commonly, you know,

13:25

sometimes you're, oh, it's sort of microcystic,

13:27

or it's sort of lobulated, or, you know, maybe

13:29

those occasional cases where you have the scar.

13:31

But to get both microlobulated and microcystic

13:35

or to actually have the scar is not every case.

13:37

Okay?

13:37

So, sometimes you're gonna have serous

13:39

lesions and not be able to be confident.

13:41

That one yesterday, it was primo.

13:43

I, I felt comfortable putting in the report that

13:46

it was, uh, almost certainly a cystic neoplasm.

13:51

And there it is.

13:52

If you forgot what it looked

13:53

like from a few moments ago.

13:55

Okay, so that's benign.

13:57

What about malignant?

13:58

So, a couple things that can point

14:00

us in the direction of malignancy.

14:02

The number one is not a radiology thing at all.

14:04

It's actually symptoms.

14:06

So, if you've got one of these cystic pancreatic

14:09

lesions and the patient is actually symptomatic

14:11

from it, and that can be a number of different

14:13

types of symptoms, obstruction, jaundice, pain,

14:16

um, that has a high correlation with malignancy.

14:20

Now, in terms of radiology stuff, uh,

14:23

since that's what we're more concerned

14:25

with, um, what are worrisome features?

14:28

Uh, nothing shocking on this list.

14:30

These are the sorts of things that we

14:32

look for in every cystic mass to decide

14:34

whether it might be malignant or not.

14:36

So, we're looking essentially

14:38

for soft tissue components.

14:39

So, things like septations, and more

14:42

septations is worse than fewer.

14:43

Septations, and thicker septations

14:45

are worse than thin septations.

14:47

You're looking for solid components, mural

14:49

nodules, certainly anything that's enhancing,

14:52

that is the, uh, you know, worst of it.

14:55

And then the other feature that we like

14:58

to take into consideration is cyst size.

15:02

And, um, it used to be set

15:05

at three centimeters that we started

15:08

to get pretty worried about cyst size.

15:11

That sort of, um, diminished a bit in recent

15:15

recommendations, and I'll talk about that

15:16

later, down to about 2.5 centimeters or 25

15:20

millimeters is what starts to get our attention.

15:23

I keep the three, uh, centimeter or 30

15:25

millimeter number in here because it has an

15:27

interesting, um, correlation to outcomes.

15:32

The likelihood of having malignancy in an

15:36

otherwise simple-looking pancreatic cyst

15:40

that is three centimeters big is about 3%.

15:45

Okay, so if you've got no septations, no enhancement,

15:48

nothing like that, it's just a cyst sitting there.

15:51

It's three centimeters, it's about a 3% likelihood.

15:54

Now, you know, that's still

15:56

like, I mean, it's not great.

15:58

I mean, you don't really want something with

15:59

a 3% likelihood of being malignant, but it's

16:01

not awful, like, in the spectrum of medical odds.

16:05

So, why was this sort of initially set as the size

16:09

where we often recommended cutting these things out?

16:13

And the reason is because nationwide, the mortality

16:17

from a Whipple procedure, uh, which is what you

16:20

have to do to get a lot of these out, is about 3%.

16:23

So, this was sort of the intersection between the

16:27

risk of the cyst being equal to the risk of the cure.

16:32

Okay.

16:32

And that's why that number was initially selected.

16:37

Now, here are some examples of these,

16:40

uh, malignant features for us to review.

16:42

So, here we've got a cystic lesion

16:44

in the body tail of the pancreas.

16:46

We see some septations within it.

16:48

It looks like there might be some

16:49

solid enhancing component here.

16:51

The wall is kind of thick.

16:53

Here we see some more wall thickening.

16:55

It's not simple.

16:56

There's a lot going on.

16:57

It looks like there's enhancement.

16:58

This is extremely worrisome for malignancy.

17:01

And this was a mucinous cystadenocarcinoma here.

17:05

Another one, different patient, uh,

17:07

different lesion, very similar appearance.

17:09

So, you know, this thing might have

17:11

started out looking more purely

17:12

cystic, but developed solid components.

17:14

Septations, thick wall.

17:17

Uh, this is very concerning for malignancy.

17:19

Here it was at a PET scan

17:21

showing its, uh, avid uptake.

17:25

Here, a very dilated pancreatic duct.

17:28

This was an intraductal papillary mucinous

17:30

neoplasm, and we can clearly see the solid

17:33

enhancing soft tissue components within it.

17:35

So, certainly this is worrisome for

17:37

malignancy, and it was, uh, malignant.

17:41

Okay, so we've been over a lot

17:43

of different, uh, features.

17:47

How do we do at predicting what these

17:51

lesions are, using all of these features?

17:54

And this is actually a, a one of these

17:57

studies came out of, um, UCSF some years ago.

18:00

So, we sort of still like to chuckle

18:02

about it since we were directly involved.

18:05

But they took the abdominal imaging, uh, section

18:08

and, um, gave us a bunch of cystic pancreatic

18:11

lesions at CT and MR, told us to look at them

18:14

and come up with what our leading diagnosis was.

18:18

Did we add it to this big four?

18:20

Was it a pseudocyst, was it a serous lesion?

18:22

Was it a mucinous lesion?

18:24

And when we did that, we were correct about

18:27

40% of the time, a little bit better than

18:30

40% of the time with our leading diagnosis.

18:32

So, not very good.

18:34

So, then they said, okay, this isn't working.

18:36

So, we're gonna just look at

18:37

cases where you're really sure.

18:39

So, the ones where you're greater than 90% certain,

18:41

this definitely looks like a pseudocyst, or

18:43

this definitely looks like a

18:44

serous neoplasm, or whatever.

18:46

And with, if we did that, and only, you

18:49

know, considered those really classic ones,

18:51

the accuracy went all the way up to about 50%.

18:54

So, about as good as random guessing.

18:56

So, we are not very good, even using all of

18:59

this morphology that I have described, at

19:02

making a definitive diagnosis just at imaging

19:06

between these different types of lesions.

19:08

So, that's not great news since, you know,

19:11

that's sort of what we set out to do.

19:13

Now, if you are just focusing on, does

19:16

this lesion look malignant right now?

19:19

Is this something that has malignantly degenerated?

19:22

We're pretty good at that.

19:23

We're reasonably accurate at that, but, uh, lots.

19:28

Using sort of the criteria that are set out for

19:32

how we manage these things, and using the imaging

19:34

features we have to look at these things,

19:36

a lot of benign lesions end up getting

19:40

overtreated. You know, you're cutting out

19:42

cystic lesions that then turn out to be nothing.

19:44

And we know that if, even, you know, if a

19:46

three-centimeter, uh, otherwise simple-looking

19:49

mass only has a 3% chance of malignancy,

19:52

and we're saying cut them all out, you

19:54

know, a lot of them are going to be benign.

19:57

And this is sort of like the

19:58

problem, this little guy right here.

20:00

So, it's, it's not that big.

20:01

It's about two centimeters.

20:03

Totally simple-looking, no

20:04

complexity, no enhancing components.

20:06

But this thing turned out to

20:08

be a mucinous adenocarcinoma.

20:11

It is really difficult to be certain

20:14

about these mucinous lesions.

20:15

They can be really, really tricky.

20:18

Now, before I move on to the management,

20:20

I wanna talk a little bit more about, um,

20:22

just incidental smaller pancreatic cysts.

20:27

Um, because these come up absolutely all the time.

20:29

There are a number of long-term studies

20:31

that have looked at their behavior over

20:33

the time, and they have shown that the vast

20:35

majority are indolent in their behavior.

20:37

They don't tend to do anything very quickly.

20:40

Some are even non-neoplastic.

20:43

One study that looked at incidental cysts

20:45

less than two centimeters, about 40% of them

20:48

increased in size over a mean of nine years.

20:51

So, they were growing over a decade,

20:54

but none became symptomatic.

20:56

Nobody died from 'em.

20:57

So, they're not doing anything quickly and they're

20:59

not doing anything too bad even over a decade.

21:02

Another study that looked at incidental

21:04

cysts, mean size of two centimeters,

21:07

90% showed no growth over two years.

21:10

So, two years probably isn't long enough

21:12

to say what these things are gonna do over

21:14

time, but it does tell you that most of these

21:16

things are not doing anything very quickly.

21:20

Now, if we look at the component of these

21:22

that do turn out to be IPMN, there's actually

21:25

a lot of sort of long-term path data, more

21:27

than there is, uh, long-term radiology data.

21:30

Genetic studies show that low

21:32

grade dysplasia in these IPMN, uh,

21:37

progressing to invasive malignancy can

21:39

occur over a period of 15 to 20 years.

21:43

So, really slow-acting, but can do

21:45

this over a long period of time.

21:47

And clinical studies have shown that benign, um,

21:50

or, uh, IPMN that have benign morphology at imaging

21:55

can suddenly start growing and progress to malignancy

21:58

after being pretty stable for about 16 years.

22:02

Okay, so these things are tricky, can change at the

22:05

last minute, sort of the teaching point there.

22:09

So, that brings us to our dilemma that although some

22:12

features can suggest a mucinous tumor, um, or a

22:16

malignant tumor, it's usually impossible to exclude

22:20

that you are looking at a mucinous lesion and maybe

22:24

even a malignant lesion just on the basis of imaging.

22:28

So, what that leaves us with is having to come up with

22:32

some sort of management system where we assume that

22:36

all of these cystic masses are potentially mucinous.

22:43

So, how are we gonna manage these guys?

22:46

Now, what in the world do we do with this mess?

22:48

So, it's true that our reports, uh,

22:51

often end up being a little bit vague.

22:53

I've certainly dictated something like, this may

22:54

be a pseudocyst or cystic pancreatic neoplasm

22:57

because we can't reliably differentiate.

23:01

So.

23:02

What can we do to help us and

23:04

further characterize, um, MRCP?

23:06

If you haven't done an MR, MRCP can be useful because

23:09

we can, uh, look for communication with the duct.

23:12

That might suggest that we're looking at an IPMN.

23:15

Um, it also, um, you know, is a little bit

23:18

better with the T2 weighted images to look for

23:20

internal complexity, make out septations, mural

23:23

nodules, uh, and those sorts of features that

23:26

might prompt us to take a more aggressive course.

23:29

If we're worried about malignancy, uh, we can of

23:32

course follow these, which ends up being like a

23:35

big thing that we do in managing these lesions.

23:39

And we can also consider, um, at

23:41

different points, endoscopic ultrasound.

23:43

Now, what's

23:44

the deal with endoscopic ultrasound?

23:45

We'll talk about that in just a second

23:47

after this pretty picture of the MRCP, where

23:49

we have this little cystic lesion and we

23:52

see so nicely, I'm gonna mag it up there,

23:55

the communication with the main duct that looks like

23:58

a little apple hanging from a tree branch, or a little

24:00

cherry or something with the little sort of stem

24:03

connecting up to the main duct is a perfect appearance

24:06

to suggest a small IPMN. Now, endoscopic ultrasound.

24:11

So, um, there are very, um, prescribed recommendations

24:15

for when, uh, this can and should be used.

24:19

And I will sort of bring up those

24:21

slides in a few moments, but.

24:23

As a general rule, I keep in my mind that it's

24:26

probably reasonable to consider endoscopic

24:29

ultrasound anytime you've got a cyst that's

24:32

bigger than about one and a half centimeters.

24:34

And you would do something about the cyst based on

24:38

the patient's, uh, age and comorbidities and stuff,

24:41

like, you know, you don't need to do an endoscopic

24:43

ultrasound and put a needle into the cyst of, like,

24:46

a 90-year-old if you're not gonna do a Whipple, if

24:48

you find mucin or, um, malignant cells or something.

24:51

But if you would act on it and it's bigger than about

24:54

1.5 centimeters, it may give you more information.

24:58

Okay, so.

25:01

It seems like if you do this and we have this tool

25:05

like in these slightly larger cystic lesions where

25:08

we can get a good look at them with ultrasound, we

25:10

can stick a needle in it and actually get cytology.

25:13

That should be sort of like the end all be all.

25:16

We can just pop that needle in, get the

25:18

answer, and not have to follow all of these,

25:20

but it's not as good as you would hope.

25:22

They actually tend to have a pretty

25:24

poor yield, uh, with cytology.

25:27

Uh, they get serous epithelium in only about a

25:30

fifth of the cases, uh, where they're needling a

25:33

serous neoplasm, uh, malignant cells in only about

25:37

half of the, uh, mucinous cystadenocarcinomas.

25:41

Now, if you do get mucin, that of course

25:43

at least tells you it's a mucinous lesion,

25:45

but you're still gonna be in a situation

25:46

where you have to follow it long term.

25:49

Uh, they can do cyst fluid analysis, which can

25:52

give us some hints, amylase, uh, if it's low,

25:54

you're probably not looking at a, uh, pseudocyst.

25:58

If CEA is high, that suggests a mucinous lesion.

26:01

But again, it's more sort of helpful and guiding,

26:05

but it is not always a definitive answer, which

26:07

is why it's not done in every single case.

26:11

So, we get to the management.

26:13

There are three things we need to consider

26:16

as we sort of, like, jump into this

26:18

mess of managing cystic lesions.

26:20

Number one, uh, does the patient have symptoms?

26:24

Number two, is the lesion complex?

26:27

Does it have malignant features?

26:29

And number three, how big is it?

26:31

So, it really breaks down simple.

26:33

And I like to break it down into simpler chunks

26:35

because, like, when you look at the whole thing

26:37

at once, it's really sort of overwhelming.

26:39

Okay.

26:40

So, one, two, and three.

26:42

One, this is easy.

26:44

Okay.

26:45

If the patient has symptoms, that's usually

26:47

going to come out because, number one, it's

26:49

causing them some sort of symptomatic problem.

26:51

And we also discussed earlier when we

26:53

talked about malignant features that

26:55

symptoms are predictive of malignancy.

26:58

So, if the patient is able to have surgery,

27:00

usually symptomatic masses will be removed.

27:03

So, easy, one whole section done.

27:06

Section two.

27:08

Um, this is, uh, a sort of generalized

27:11

guideline that I adapted from, um, international

27:15

consensus criteria that came out in, uh, 2012.

27:18

This is not from ACR, but I like this, uh, because

27:22

it is just a sort of general, sensible way of

27:25

thinking about these things, that if you have some

27:29

of the malignant features that we have seen at

27:32

imaging, so septations, nodules, enhancing components.

27:35

Enhancing components, those are coming out.

27:38

If it's the sort of lesser malignant features, so

27:41

the thickened walls or nodules that are not clearly

27:44

enhancing, lots of septations, that sort of thing.

27:47

That is when they recommend performing

27:50

endoscopic ultrasound because it has malignant

27:53

features, but it's the definitive group.

27:56

And then, um, based on the ultrasound appearance

27:59

and the cytology, if it's sort of, you

28:02

know, confirmed we've got like soft tissue,

28:05

we have positive cytology, those come out.

28:08

And if it's sort of like, ah, I'm not sure,

28:10

it could just be debris or something, and we

28:12

didn't really get anything on cytology, then

28:14

those are going to just go into an imaging

28:17

follow-up category, but the endoscopic

28:19

ultrasound helps us decide which ones have

28:22

to come out now and which ones can we keep

28:24

watching if they have complex features.

28:27

Now, the last, uh, category is size, and this is

28:31

where it starts to get, like, really muddled, is

28:34

when we start trying to determine what we should

28:37

do about these things just based on how big they

28:41

are, knowing that they could be, like, any one of

28:44

those big four sort of cystic lesions in reality.

28:48

Um, and all we have to go on is size.

28:51

So, uh, there were the consensus guidelines

28:55

that came out in 2012, and then we had

28:57

these old ACR, uh, guidelines from 2010.

29:02

Um, and.

29:03

For a period of, what, maybe

29:06

like five years or something.

29:08

It was very difficult to sort of practice, uh,

29:12

with these two sets of guidelines out there because

29:15

they were, like, completely opposite of each other.

29:19

Okay.

29:20

And I thought, oh, here it is here.

29:22

So, these were the 2010 ACR Incidental

29:26

Finding Committee guidelines.

29:27

And the, the area where it was

29:29

so problematic was the smaller cysts.

29:33

And unfortunately, that's probably what we

29:35

deal with most commonly throughout the day,

29:38

where you're coming up with like, oh, a little

29:39

cyst in the pancreas or a little cyst there,

29:42

uh, cysts that were less than two centimeters.

29:44

The ACR was saying that if you get a single

29:47

follow-up, uh, preferably by MR, so we could

29:50

see the characteristics well, and it was stable,

29:54

uh, for one year, that we could determine that

29:57

it was benign and not follow it up anymore.

30:01

So, you know, that sounds easy enough, but

30:03

the consensus guidelines said there's no good

30:06

long-term data to support that follow-up can

30:09

be discontinued even after long-term stability.

30:12

And they were sort of, you know, basing that on those

30:15

pathologic studies that I talked about and such.

30:18

Uh, so this was like difficult because all of the,

30:21

like oncologists and, um, you know, surgeons and

30:25

everyone in our hospital were sort of going off

30:27

these consensus guidelines, and then us in radiology,

30:29

we had this like extremely discordant thing.

30:32

So, I actually was not recommending this

30:34

back at this time, uh, because it

30:37

just wasn't helpful to our clinicians.

30:39

Uh, luckily, the good news is this has gone away.

30:44

And we have new ACR guidelines that came out in 2017.

30:49

So, the good things about these new guidelines is

30:52

that they're much more rational and evidence-based,

30:55

and they're looking at the, you know, same data

30:57

that the consensus, uh, guidelines were based on.

31:01

They're much more concordant

31:03

with those consensus guidelines.

31:04

And now we're sort of acting similarly

31:07

to our colleagues in other fields.

31:09

But the bad part about it is that

31:12

they are way more complicated.

31:14

I'm still sort of hoping for version 3.0 where

31:17

we get like the next version of ACR guidelines

31:20

where they're, you know, similar to what they're

31:23

recommending now, but a bit more simplified.

31:25

Because right now it reminds me a little bit

31:28

of this, and this is, I swear, a railroad sign.

31:30

I was in, um, Iceland a few years ago.

31:34

At a radiology conference actually, and,

31:36

uh, driving along the road, and my friend

31:39

was actually driving, I said, stop the car.

31:41

I have to take a picture of this road.

31:43

Sign for my pancreatic cystic masses talk.

31:46

Uh, because here we go.

31:48

As we sort of jump into this, there are, you know,

31:50

about 10 different algorithms that look like this.

31:54

And it's probably a good, you know, practice just

31:57

to, you know, put a PDF of this paper on your laptop.

32:01

Um, and, you know, pull it up, uh, in

32:03

the cases where you need more specific

32:05

guidance because it's impossible to

32:06

memorize every single little facet of these.

32:09

But I'm gonna sort of go over the big differences

32:12

and the big points you need to know, uh, quickly.

32:15

So.

32:16

New guidelines for small cysts, less

32:19

than about a centimeter and a half.

32:21

Uh, that's what we're looking at here.

32:22

A couple things to notice.

32:24

Number one is they break it up based on

32:29

patient's age, what the exact recommendation is.

32:32

And this is different from how it used to be in 2010.

32:34

So now we consider these differently.

32:36

Um, if the patient is younger or older,

32:39

it's the younger patients where you

32:40

wanna be a little bit more aggressive.

32:42

I just remember this generally as being

32:44

retirement age, or I use the Beatles song,

32:46

you know, 64, it's actually 65, but it gets

32:49

me close enough when I'm reading cases.

32:51

So if they are younger than 65, um, you wanna

32:55

follow these for, uh, a year, a year, a year,

33:00

every year for the first five years, and then

33:02

you can widen it to, uh, every two years.

33:06

The other difference is that all of the

33:09

recommendations across the board, we are

33:11

following these for at least 10 years.

33:13

The older age group, we can start at two years.

33:16

So two years, two years.

33:17

Two years.

33:17

Just for a total of 10 years.

33:20

Um, 10 years.

33:21

So why that number?

33:23

I think it's probably just sort of like,

33:24

was a reasonable compromise if we've

33:26

got these pathology studies saying this

33:28

can happen over 30 years or something.

33:30

But, you know, think about our old recommendations

33:33

for, you know, small cysts like this.

33:35

We used to say, follow it for one

33:36

year, and if it's stable, you're done.

33:39

Now we're saying, look, we have

33:40

to follow these for a while.

33:41

Make sure they're not growing,

33:43

not acting aggressively.

33:45

We're gonna do it for 10 years,

33:47

and how frequent we're gonna do

33:48

it depends on how old the patient is.

33:50

We're gonna be more aggressive

33:51

in the younger patients.

33:53

Um, so this is reasonable.

33:55

I think, I think it's a good compromise.

33:56

You know, if you're in this older

33:58

group, it's just five scans.

33:59

It's, you know, every two years, it's,

34:01

it's, uh, you know, the best we can do

34:03

with the data we have at this point.

34:06

Now, once the lesions start getting a little

34:08

bit bigger, so in this 1.5 to 2.5, um, category.

34:14

They, uh, make a distinction between, oopsie, uh, let

34:18

me go back, between lesions that either communicate

34:21

with the duct or do not communicate with the duct.

34:24

So what does that mean?

34:25

It probably means that the ones that communicate

34:29

with the duct are more likely to be IPMNs as

34:32

opposed to, like, maybe a mucinous cystic neoplasm,

34:35

which doesn't usually communicate with the duct.

34:38

So IPMN, a little more benign, acting a little

34:41

more indolent in their behavior, so we don't

34:44

have to follow them quite as aggressively.

34:46

And that's what this algorithm represents.

34:49

Now, they're gonna break it up a bit by size.

34:51

Sorry about that.

34:52

My slides are getting, uh, over anxious there.

34:55

So the smaller ones, again, you can follow those a

34:58

little less frequently, starting at, um, once a year.

35:02

Um, if it gets a little bigger,

35:04

bigger than two centimeters.

35:06

Two centimeters should be like a trigger that

35:09

an annual follow-up probably isn't adequate

35:11

for something that's two centimeters.

35:12

We're gonna start those at six months, and once

35:15

we start getting into all these convolutions,

35:17

you know, I have like sort of generally memorized,

35:20

like, oh, this I can do two years, this I

35:22

can do one year, this I can do six months.

35:24

But once it sort of starts going down

35:25

these pathways, like has it grown?

35:28

You know, is it still this big?

35:30

When should I image it?

35:31

I just, like, pull up the algorithms.

35:33

I think it's very, very difficult to memorize

35:35

all of the very specific circumstances.

35:38

So if they do not communicate with the duct here,

35:41

we're worried about them maybe being the mucin

35:43

cystic neoplasms, we're going to have to be a

35:46

little bit more aggressive because those lesions

35:48

can grow faster and be a little bit more aggressive.

35:50

So regardless of how big it is, you know,

35:53

if it's, you know, anywhere in this range,

35:56

notice that they're not breaking this up

35:57

to 1.5 to, you know, 1.9, and two to 2.5.

36:01

It's the whole group.

36:03

Um, if they don't communicate with the duct,

36:05

you're gonna start at about six months.

36:07

Okay?

36:07

So communication with the duct

36:09

can buy you less frequent scans.

36:14

Now, this is sort of our worst

36:16

size category, greater than 2.5.

36:19

Used to be greater than three.

36:20

It's been changed to greater than 2.5.

36:23

And this is where you probably want to start

36:26

considering taking these out, just, uh, as we

36:29

did with the three centimeter criteria before.

36:32

But, uh, it's a little bit more flexible than the old

36:36

criteria were before. It just said greater than three

36:38

centimeters, you know, surgical resection, but you

36:41

know, if greater than three centimeters, which is a

36:43

3% risk, and that Whipple can kill you that day, and

36:47

the cyst is probably gonna take longer to kill you,

36:50

I'm not sure that even I, with a three centimeter cyst,

36:53

would be, like, rushing in for my Whipple that day.

36:56

So I think this is totally reasonable.

36:58

Um, they give you the flexibility to follow these

37:01

larger lesions over time and see what they're doing.

37:04

They don't all have to, like, rush off to the

37:06

OR, but you wanna follow them at pretty

37:08

um, close, uh, intervals.

37:11

So the, the shortest one is gonna be about

37:14

six months, and it can get more, you know,

37:16

frequent than that depending on what it's

37:19

doing, if it's growing, and so on and so forth.

37:24

Now, uh, a sort of, um, subcategory that's

37:27

quite helpful is if you identify one of these

37:30

cysts in a patient who is over 80 years old

37:34

at the time you first identify it, um, you

37:37

don't have to follow these, uh, for very long.

37:40

So you can follow them for just four

37:42

years, and it's usually at two years, and

37:44

then another scan, um, at four years.

37:48

So just two scans over a period of

37:49

four years, and then you're done.

37:52

So, uh, whenever I see one of these, now, it's the

37:54

first thing I do is I check the age, not just to see

37:57

what category it's putting me into, but to, you know,

37:59

what I'm hoping to see is that the patient is over

38:01

80, and then we can do a shorter period of follow-up.

38:06

One exception, uh, to that complicated

38:09

set of algorithms is the white dot.

38:11

So if you have just a teeny, tiny little cyst, the

38:15

kind of cyst that you're probably not even gonna

38:17

see at CT, but have a better chance of seeing

38:20

at MR, uh, because they are so bright at T2.

38:24

Um, the white, so-called white dot, these are

38:28

generally gonna be less than about half a centimeter.

38:31

So five millimeters or less. These are quite common.

38:33

We see them retrospectively at

38:35

CT in a few percent of people.

38:36

But at MR, we see them retrospectively

38:39

in up to 20% of people.

38:42

Uh, the prevalence increases

38:44

with age. We don't even report

38:46

um.

38:47

Very many of them because we're

38:48

just sort of, like, looking over them.

38:50

They're such tiny little findings.

38:52

There is an exception that if you've just got one

38:55

of these white dots, you can follow it at CT or MR

38:59

after two years, and if it's stable, then you can stop.

39:02

So that's sort of actually similar to the old ACR

39:05

criteria, but they're just talking about these teeny,

39:07

tiny, like, little five millimeter ones, not, you

39:10

know, anything bigger, like a 1.5 centimeter lesion.

39:15

If the patient's over 80, you can maybe pretend

39:17

you don't even see it and don't report it.

39:20

So, uh, our summary of changes to the ACR

39:23

guidelines, we've got slightly different

39:26

size categories, uh, than we did before.

39:29

This is how they break down.

39:31

We're following cysts longer for a period of

39:34

10 years, which is probably a good compromise.

39:37

The lesions are generally managed as mucinous unless

39:40

proven otherwise by endoscopic ultrasound.

39:43

We have different recommendations based on

39:46

whether they communicate with the duct or not.

39:50

There's greater use of endoscopic ultrasound sort

39:54

of built into all those algorithms at different

39:56

points where we can get some extra information there.

40:00

And there are different recommendations based on age.

40:05

And I know it gets sort of frustrating

40:07

sometimes reporting all of these,

40:09

particularly when they're tiny little guys.

40:11

So I like to leave you with this cautionary

40:14

example of this patient who had just

40:16

the tiniest little IPMN-looking thing in

40:18

the pancreatic tail back in, um, 2014.

40:22

By 2015 it was, you know, was it a little bigger?

40:25

Was it not?

40:25

Maybe a couple millimeters. 2016,

40:28

all of a sudden it was substantially bigger.

40:30

Probably, uh, should have been

40:32

um, needled at that point.

40:35

Uh, it was not. In 2017 it now had grossly

40:38

malignant features, thick wall, and the patient

40:40

actually had liver metastasis at that time.

40:43

So these things really can evolve to

40:45

generate and become malignant over time.

40:48

It is not a rumor.

40:49

It does sometimes happen.

40:51

Okay.

40:52

So with that, let's leave those cystic guys

40:55

behind and talk about some other atypical

40:58

pancreatic masses for this last part.

41:00

So what I'm gonna talk about now are neuroendocrine

41:02

tumors, the other cystic masses, and a couple,

41:06

uh, mimics of pancreatic masses quickly.

41:10

So pancreatic islet cell tumors.

41:12

Um, what we're gonna talk about here with these

41:14

neuroendocrine tumors, a little bit about, uh, best

41:18

ways to see them and, you know, what contrast phases

41:20

we need and stuff, what they look like, and how do we

41:24

tell the difference between these and adenocarcinomas.

41:27

And I sort of go to that step because

41:29

this is probably the second most

41:31

common, you know, solid pancreatic mass

41:34

you're gonna see are these

41:35

pancreatic neuroendocrine tumors.

41:38

Okay, so generally you can think of

41:41

pancreatic neuroendocrine tumors as

41:43

either syndromic or non-syndromic.

41:45

They all actually produce hormones, but

41:48

only a few of them produce, uh, an actually

41:51

clinically recognizable hormonal syndrome.

41:55

So the syndromic ones that we, you know, think

41:57

of that cause hypoglycemia, gastros that can

42:01

cause Z or Ellison syndrome or peptic ulcer

42:04

disease, those are probably the two most common.

42:06

And then some more rare ones.

42:08

Glucagon, uh, VIPomas, somatostatin is quite rare.

42:16

Non-syndromic tumors, uh, non-syndromic, uh,

42:19

neuroendocrine tumors tend to be larger, and

42:22

if they present, they're going to present

42:24

because the patient has abdominal pain, maybe

42:26

just from the mass effect from the tumor.

42:28

If they're small, they tend to be incidental,

42:30

asymptomatic, and you're probably never

42:32

going to know about a small non-syndromic

42:35

one unless you just happen to pick it up

42:37

incidentally on imaging for something else.

42:41

So what do these look like?

42:42

Let's start first with the syndromic ones.

42:44

So these are the ones that, you know,

42:46

come to attention because of symptoms.

42:48

So we're more likely to see them when they're

42:50

smaller, and they do tend to be small little

42:52

lesions, smaller than three centimeters.

42:55

The smaller they are, the more

42:57

homogeneous they tend to look.

42:59

So in general, we're thinking

43:00

something small, something homogeneous.

43:03

Here's a nice example.

43:05

We see this mass, small, less than three centimeters,

43:08

homogeneously enhancing in the pancreatic head.

43:12

Good look for a syndromic neuroendocrine tumor.

43:15

Now, they also tend to be hypervascular,

43:19

as we actually saw in that last case.

43:22

But occasionally these are actually more

43:26

conspicuous in the portal venous phase.

43:28

So they're supposed to be hypervascular, we're

43:30

supposed to see them best at arterial phase.

43:33

Does not happen in every case.

43:35

Occasionally, you see these sort of oddballs,

43:38

uh, and when they do look more hypovascular,

43:42

that's usually a predictor of a poor outcome.

43:45

So it's one thing you actually wanna

43:47

pay attention to for prognosis, is,

43:49

is it hypovascular, or is it hypervascular?

43:52

So here, an example of a classic hypervascular one.

43:55

We actually see it quite nicely both on

43:58

the arterial phase and the portal venous

44:00

phase, small, homogeneous, hypervascular.

44:04

Uh, read the textbook.

44:06

Here's one that we see on the

44:08

arterial phase quite nicely.

44:10

It's hypervascular.

44:12

On the portal venous phase, it's really hard to see.

44:14

So here, uh, you know, if we didn't have

44:16

that arterial, it could be easy to miss

44:19

this one.

44:21

This one is actually more conspicuous.

44:24

On the portal venous phase.

44:25

You can see it on the arterial, but it

44:26

stands out a little bit less compared to

44:29

the portal venous, where the rest of the

44:31

pancreatic parenchyma enhancing nicely.

44:33

This one is more hypovascular,

44:35

probably worse prognosis.

44:38

Now, what about location?

44:39

This is something, when you first start reading about

44:41

these, there's all of these, like, you know, different

44:43

locations, uh, subscribed to them, and they do have

44:46

different locations where they tend to be more common,

44:48

but there's too much overlap for it to be that useful.

44:51

So that's like the good news is you don't, there's not

44:53

really any reason to memorize it with one exception.

44:57

And the one exception is in the case of suspected

44:59

gastrinoma, uh, these can, uh, frequently be

45:03

extra-pancreatic and often small and multiple.

45:07

So remember we have that gastrinoma triangle, which

45:10

is sort of like this entire area that includes the

45:12

pancreatic head and a lot of the first and second

45:15

portion of the duodenum and around, you know,

45:18

the fat around the common bile duct and such.

45:21

Um, and.

45:22

That sounds like very sort of old

45:24

medical school information that you're

45:26

supposed to be allowed to forget.

45:28

But if you do not look for these little tiny

45:31

multifocal gastrinomas, you are going to miss them.

45:33

Like, here's an example.

45:35

Uh, we were asked to look for neuroendocrine tumor.

45:37

You know, you look in the pancreas, there's

45:39

nothing big, you're gonna sort of pass

45:40

along, but look at these little things.

45:42

So there are all of these tiny little hypervascular

45:47

nodules embedded, not just in pancreatic

45:49

parenchyma, but in the wall of the duodenum.

45:53

This was multifocal gastrinomas.

45:58

So gastrinomas, as we just saw, often extra-

46:01

pancreatic, multiple, and small, that is

46:04

often associated with patients that have MEN

46:06

You can have solitary,

46:09

larger gastrinomas in the pancreas.

46:12

Uh, those do not tend to be associated with MEN

46:15

1, and they have higher malignant potential.

46:17

So you actually would sort of prefer to

46:19

see this pattern of small, multiple ones.

46:21

It's a more benign pattern.

46:23

Here are a couple more examples.

46:25

A tiny little gastro in the duodenum at that arrow.

46:28

And then the second one, actually hard to see

46:30

because it's larger right there, almost blends in

46:33

with the cava, but a larger, uh, duodenal gastro.

46:39

Now, non-syndromic, uh, neuroendocrine tumors, again,

46:43

these are going to grow bigger before they present.

46:46

Uh, they tend to be larger.

46:48

And they tend to be more heterogeneous, often having

46:51

areas of cystic degeneration or calcification.

46:55

So this is a good look for a non-

46:57

syndromic neuroendocrine tumor.

46:58

Much uglier, much larger, cystic areas, calcification.

47:02

The larger they are, again, the more

47:04

likely they are to harbor malignancy.

47:09

Now, how can we, uh, reliably tell the difference

47:11

between a neuroendocrine tumor and an adenocarcinoma?

47:14

When we're looking at studies, there are a ton

47:17

of, you know, classic features for these, uh,

47:19

neuroendocrine tumors, and they tend to be pretty

47:21

opposite of the features of adenocarcinoma.

47:23

So I'm gonna go through them, and

47:24

then I'm gonna show you examples.

47:26

So, number one, we know they tend to be hypervascular.

47:29

They also tend to have very discrete borders,

47:32

and I'll show you some examples of that.

47:34

They are sometimes exophytic in morphology.

47:38

They're more likely to have cystic components or be

47:40

cystic. Uh, if they involve vessels, it tends to be

47:44

intravascular extension versus vascular encasement.

47:48

And they don't typically obstruct the duct.

47:53

So here, side by side.

47:55

We have an adenocarcinoma, hypodense, ill-defined,

47:59

centered in the gland, and the islet cell

48:02

tumor, hypervascular, extremely well-defined.

48:05

We could draw a line right around

48:07

this thing, and partially exophytic.

48:10

Very different appearances.

48:12

Uh, very opposite of each other here.

48:15

Um, just looking at the density of these lesions.

48:18

So adenocarcinomas, again, low density,

48:22

but don't often become cystic or necrotic.

48:25

They can, but it is not a common feature.

48:28

The islet cell tumors do it much more often

48:31

where you actually get cystic degeneration.

48:36

Vascular involvement.

48:37

So adenocarcinomas classically encase the

48:40

vessels, often obstructing them in that way.

48:43

Uh, neuroendocrine tumors, they're not

48:45

famous for this, but they absolutely do it.

48:47

They, when they involve vessels,

48:49

tend to invade the vessels.

48:52

Uh, we see tumor thrombus in this case,

48:54

uh, climbing into the splenic vein here.

48:57

Another, uh, some other examples with,

49:00

uh, um, vascular invasion into the portal

49:03

venous system can be present as tumor thrombus

49:07

in islet cell carcinomas in about 5% of cases.

49:10

So it's not every case, but it does

49:12

happen, and it is under-reported.

49:14

So it's a feature that you should look for.

49:17

Ductal obstruction.

49:18

We know pancreatic adenocarcinoma

49:20

loves to obstruct the duct.

49:21

Pancreatic islet cell tumors tend not to do

49:24

it, even when the mass is in a position where

49:27

it seems like it should obstruct the duct.

49:30

So here we're seeing a lack of ductal dilation,

49:34

pancreatic adeno here with the ductal obstruction.

49:38

Islet cell here.

49:39

No ductal obstruction.

49:42

Now, every once in a while, you'll see a

49:44

mass that looks like a neuroendocrine tumor.

49:46

It's hypervascular, it's obstruct-

49:48

but it's obstructing the duct.

49:49

And then you think, what, what is this?

49:51

Is it a weird neuroendocrine tumor

49:53

or is it a weird adenocarcinoma?

49:55

Uh, it does happen.

49:56

Sometimes it can indicate that it is

49:59

going to be a more aggressive tumor.

50:01

Um, but also you can see this in just a small subset

50:05

of neuroendocrine tumors that secrete serotonin.

50:08

So in these, uh, serotonin-secreting neuroendocrine

50:10

tumors, think of carcinoids or something where you

50:12

get that sort of retractile appearance and fibrosis.

50:15

It can induce fibrosis that can obstruct the duct.

50:18

So when you see a hypervascular mass with

50:21

associated ductal dilation and atrophy, like this

50:24

tiny little mass here with all of this ductal

50:27

dilation, all this glandular atrophy, that is

50:30

classic for these serotonin-secreting tumors.

50:34

Another weird-looking one.

50:36

It's hypervascular, but it's causing

50:38

very profound, uh, ductal obstruction.

50:42

This was actually a bizarre-looking

50:44

adenocarcinoma that was denser than

50:46

usual and had cystic degeneration.

50:49

So again, the ductal obstruction

50:51

tends to suggest adenocarcinoma.

50:53

This looked quite cystic.

50:55

Uh, you think, is it a cystic neuroendocrine tumor?

50:58

But there was ductal dilation.

51:00

This also turned out to be another weird

51:02

case of cystic degeneration of adeno.

51:05

This was one where I thought,

51:07

what in the world is this?

51:08

Because it's a little hyperdense.

51:09

It's very well-circumscribed.

51:11

That would seemingly go for neuroendocrine,

51:13

but very atrophic, big ductal obstruction.

51:17

This actually turned out to be, it didn't

51:18

make sense for neuroendocrine or adeno.

51:21

It turned out to be an oddball.

51:22

This was acinar cell carcinoma.

51:26

Lymphoma, just to remind you, a tumor famous for

51:30

uh, involving organs without causing obstruction.

51:33

No ductal obstruction. Lymphoma, in the rare cases

51:35

that you have lymphoma involving the pancreas.

51:39

Now, just a moment about other cystic lesions.

51:43

So we've talked about, um, all of the

51:47

big four cystic lesions of the pancreas.

51:49

The other tumors that can sometimes look cystic,

51:52

I've just told you that islet cell tumors

51:54

can sometimes cystically degenerate.

51:56

There's also a rare tumor called solid and

51:58

papillary epithelial neoplasm, or SPEN.

52:02

And then I've already mentioned that

52:04

occasionally ductal adenocarcinomas can

52:08

sometimes cystically degenerate.

52:10

So here, the islet cell tumors,

52:12

we've already looked at these.

52:15

But here's our new one.

52:16

This is the SPEN.

52:17

So these things all look very similar.

52:19

Big mass, tail of the pancreas, sort of this

52:22

cloudy appearance with low-level enhancement.

52:25

This was also a 21-year-old woman,

52:27

which is the classic demographic.

52:28

So young patient, big thing at

52:31

the tail, cloudy appearance.

52:33

Think of SPEN.

52:35

So what are these things?

52:36

They're pretty rare.

52:37

About 1% of pancreatic tumors,

52:40

again, occurring in young women.

52:42

They can have these associated clinical findings

52:44

of eosinophilia and polyarthralgias.

52:47

And they're a low-grade malignancy.

52:49

So usually you can just cut these

52:50

out and the patients do fine.

52:52

Um, what we're looking for, the things I've

52:54

already talked about, this sort of hazy, kind

52:56

of combined solid-cystic appearance, often looks

52:59

kind of cloudy, that can contain hemorrhage,

53:03

calcification, sometimes peripherally.

53:06

Sometimes stippled, and they

53:08

don't tend to enhance that much.

53:10

So here's another example.

53:11

A 19-year-old woman.

53:12

This big, sort of hazy, cloudy looking thing.

53:15

Coming off the pancreatic tail,

53:17

we're gonna think of a SPEN.

53:19

And then this one was weird, uh, just because the

53:22

patient was older, still a woman, but in her sixties.

53:25

And we see some of that stippled

53:26

calcification, some of the sort of hazy

53:29

enhancement, and some more cystic areas.

53:32

But big thing at the tail, you're

53:34

gonna want to think of SPEN.

53:37

Last one.

53:39

Uh, weird little

53:41

cystic looking thing that otherwise you

53:43

might think was just an adenocarcinoma.

53:46

That's what it is.

53:46

Sort of the rarer cases where adenocarcinoma

53:50

undergoes cystic degeneration.

53:52

And then to finish off in the last moment with

53:54

uh, just a couple mimics of pancreatic masses,

53:57

pancreatitis can sometimes mimic masses.

54:00

And I wanna give a mention to

54:02

the intrapancreatic splenule.

54:04

So one classic way that, um, pancreatitis

54:08

can mimic a pancreatic mass is if it

54:10

involves the pancreaticoduodenal groove.

54:13

So this space sort of between the

54:14

pancreatic head and the duodenum.

54:17

Um, if you get

54:18

localized inflammation in this space,

54:20

it can mimic a pancreatic head mass.

54:23

We see ductal dilation, dilation of the CBD,

54:26

this thing that looks like an adenocarcinoma,

54:28

but this turns out to be groove pancreatitis.

54:31

It's a rare form of chronic pancreatitis.

54:35

Um, and we're not really sure why it happens, but

54:38

it does cause, uh, obstruction of the bile ducts

54:41

and sometimes can even cause duodenal obstruction

54:44

and can mimic adenocarcinoma in those ways as well.

54:49

Um, if the abnormality looks centered more

54:53

in the pancreaticoduodenal groove than

54:55

the pancreatic head, you wanna think of it.

54:58

And, um, sometimes you can see the strange pattern

55:01

where it enhances a little bit more on delayed images.

55:04

I have to say, this is not

55:05

usually what I'm looking for.

55:06

I'm usually looking for the anatomy of it being

55:08

sort of in the pancreaticoduodenal groove.

55:12

And then when I see that, the next thing I do

55:14

is look at the duodenum, and I look to see

55:16

if that medial wall of the duodenum that

55:19

is opposed to the pancreas looks thickened.

55:21

And sometimes you can even see that

55:23

the thickening is kind of cystic.

55:25

So here you see a nice example, that

55:27

weird sort of hypodense thickening,

55:30

um, in the pancreaticoduodenal groove.

55:32

Look at the duodenum.

55:33

That wall looks very thick, and it looks

55:35

sort of edematous or cystically thick.

55:38

That's a good look for groove pancreatitis.

55:40

You're not gonna send them

55:41

straight to biopsy or Whipple.

55:42

You get a short interval follow-up scan.

55:45

And like in this case, it resolved.

55:49

A different pancreatitis case.

55:52

Um, ductal obstruction.

55:54

Pancreas has a strange, smooth appearance

55:57

in the pancreatic head, but it was big.

55:59

People were worried about a pancreatic head mass.

56:02

Here, a little bit of biliary wall thickening as well.

56:06

Now, here's another patient who has the same diagnosis.

56:09

The pancreas looks sort of effaced.

56:11

We don't have its normal lobular contour.

56:13

There's this weird hypointense rim, and

56:15

it looks sort of big and sausage-like.

56:18

And this is an entity called autoimmune

56:20

pancreatitis, sometimes spelled out as

56:23

lymphoplasmacytic sclerosing pancreatitis, or LPSP.

56:28

So, uh, uh, autoimmune pancreatitis.

56:31

Um.

56:33

It is sometimes referred to as

56:34

duct-destructive pancreatitis.

56:36

There is damage to the duct, and you

56:38

don't usually see ductal dilation.

56:41

Um, clinical symptoms can be vague and similar

56:44

to findings in adenocarcinoma, so that's

56:47

why they are sometimes clinically mistaken.

56:50

So occasionally people will actually go, uh,

56:53

forward and have a Whipple procedure, and

56:55

then on pathology they'll get back that they

56:58

actually just had autoimmune pancreatitis.

57:01

That's obviously not the treatment.

57:03

Uh, you treat these patients with

57:04

steroids, so you wanna sort of keep this

57:06

on your radar as a potential diagnosis.

57:08

What we're looking for, the

57:10

pancreas can be diffusely enlarged.

57:12

Sometimes it's just focal.

57:13

And when it's focal, it tends

57:15

to be in the pancreatic head.

57:17

There isn't going to be a

57:18

difference in enhancement though.

57:19

So it's not like adenocarcinoma where the mass is more

57:22

hypoenhancing compared to the rest of the pancreas.

57:25

It just looks sort of bulky or big.

57:28

Look for that normal, uh, contour.

57:31

The lobular contour being effaced and smooth.

57:33

I find that the most useful finding.

57:36

In some cases, you'll see that capsule-

57:39

like rim of low attenuation surrounding the

57:41

pancreas instead of the normal lobular contour.

57:44

You're not gonna see a dilated duct.

57:46

You're not probably gonna see it at all.

57:48

You're not gonna see typical findings of

57:50

findings of chronic pancreatitis.

57:52

There's not gonna be calcifications.

57:53

You're not gonna see peripancreatic

57:55

stranding or anything like that.

57:57

And we can see some of these

57:59

biliary abnormalities that we saw.

58:01

So lobular contour effaced, weird look.

58:05

Think of autoimmune pancreatitis.

58:08

And then last case, I know it's hard not

58:10

to look at the adrenal myelolipoma, but

58:12

the real finding is in the pancreatic tail.

58:15

We've got this little solid enhancing thing

58:17

right at the tip of the tail of the pancreas.

58:19

And I've already mentioned the diagnosis here.

58:21

This is an intrapancreatic splenule.

58:24

So how can we be sure that this enhancing thing is an

58:27

intrapancreatic splenule and not a neuroendocrine tumor?

58:31

Some other, you know, small

58:32

homogeneously enhancing tumor.

58:35

Well, a couple, um, things to

58:38

help us along with this diagnosis.

58:40

Number one, to make a diagnosis of intrapancreatic

58:43

splenule, you want it to be at least 180 exophytic

58:47

or uncovered by the pancreatic parenchyma, should

58:50

be sticking out at the end of the pancreas, not

58:53

completely embedded within the pancreatic parenchyma.

58:56

If at least 180 degrees is untouched

58:58

by the pancreas, think of splenule.

59:01

It has to enhance similarly to the pancreas

59:04

on all sort of phases of the CT you have.

59:07

If you have an MR, it has to have

59:08

the same signal on all phases.

59:11

And then the other thing we can look for is,

59:13

sometimes you'll see little branches of the

59:16

splenic artery actually feeding these things.

59:18

And when you see that, you can be confident that

59:20

you're looking at an intrapancreatic splenule.

59:23

Now, here's an example of an insulinoma

59:26

sort of mimicking an intrapancreatic splenule.

59:29

But here you can see that the pancreatic

59:31

parenchyma completely surrounded this thing.

59:34

So we're not going to be able to

59:35

make a diagnosis of splenule at imaging.

59:38

This did turn out to be insulinoma.

59:42

So in summary, the take-home points.

59:44

Remember, it's really difficult to

59:46

differentiate those cystic pancreatic

59:47

lesions at imaging with any reliability.

59:50

We're reasonably good at benign from

59:52

malignant, but we are bad at knowing for

59:55

sure whether something is mucinous or not.

59:57

So we're bad at determining

59:59

benign from potentially malignant.

60:01

The large ones that are bigger than about two

60:04

and a half centimeters that have complex features

60:07

or are symptomatic will often be resected.

60:10

We can now follow the ones that are not complex or

60:14

symptomatic and just larger than 2.5 centimeters.

60:19

The follow-up interval is now going

60:21

to be 10 years for simple asymptomatic cysts,

60:25

and how often we follow it is going to depend

60:28

on both the cyst size and the patient age.

60:34

The syndromic islet cell tumors can be hard to see.

60:37

Um, usually they're going to be very distinct

60:40

in their appearance compared to adenocarcinoma.

60:43

And then lastly, in addition to the

60:44

big four cystic lesions, remember that

60:46

islet cell tumors are frequently cystic.

60:49

The other cystic neoplasms tend to be pretty rare.

60:52

And lastly, keep in mind just those couple tumor

60:55

mimics, uh, that we actually see pretty frequently.

60:59

Groove pancreatitis, a form of chronic pancreatitis,

61:02

autoimmune pancreatitis, which can give you that

61:04

big sausage pancreas, and intrapancreatic splenules.

61:09

And that is it.

61:11

So thank you very much for your attention.

61:13

Um, I hope this was, uh, useful to some of you.

61:16

1402 01:01:16,140 --> 01:01:19,230 Okay everyone, as we bring this to a close,

61:19

I wanna thank you, Dr. Webb, for this lecture.

61:21

And thanks to all you guys for

61:22

participating in our noon conference.

61:24

This Noon conference is available on demand on mrionline.com.

61:27

in addition to all the previous noon conferences.

61:29

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61:32

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61:35

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