0:00

So we've gone from 21 years old to 80 years old.

0:05

He's got a painful lump on the bottom of his foot.

0:08

So I'm going to do what I, what I always do.

0:12

Painful up on the bottom of the foot.

0:14

You know, I'm thinking about

0:15

things like loose body, uh, plantar

0:19

fascial tear, plantar fibromatosis.

0:22

So I'm going to, I'm going to scroll, um, my water

0:26

weighted proton density fat suppression image.

0:29

Which, by the way, um, Vladimir and Dave,

0:33

when you're, when you're doing this,

0:34

make sure that your TE is not over 60.

0:40

You know, if your TE is approaching 60,

0:42

you're going to lose contrast properties.

0:46

So you want that TE to hover

0:48

between 40 and 55 at most.

0:52

You know, 50 is good.

0:53

45 is good.

0:54

That's kind of the range I'm at.

0:56

So you don't want your PD, uh, to have too short

0:59

a TE and you don't want it to have too long a TE.

1:03

20 is too short.

1:04

65, 70 is too long.

1:07

So we've got that nice sort of bone scan,

1:09

everything that's white is abnormal on your right.

1:13

Patient moved a little bit on your left.

1:16

And I, you know, I'm scanning for.

1:18

Plantar fascial abnormalities,

1:21

plantar abnormalities, loose bodies.

1:23

I don't see any of those things.

1:25

What I do see are some varices.

1:30

I see the obligatory sort of arthritis

1:34

in the big toe, which everybody has.

1:37

But then I see this, this puff a lump.

1:42

What the heck is this thing right here?

1:45

You know, there's all kinds of possibilities.

1:48

Uh, it's an 80-year-old man.

1:50

So maybe one of the first things that comes to

1:52

mind is gout, and then you kind of scroll

1:55

the scan and say, okay, erosions, not really.

1:58

Uh, capsulitis a little bit,

2:01

um, osteoarthritis, not really.

2:04

Um, how does the architecture look

2:06

on T1 other than the curved toe?

2:09

Pretty, pretty dang good.

2:11

Quite good.

2:12

There is the plantar plate.

2:15

There is the flexor.

2:16

Um, so there's, there's really no major

2:18

plate disruption that would explain this

2:22

and I'm, I'm giving it some dramatic

2:25

flair because it is a big round boulder.

2:29

And it looks like air is rock.

2:31

And then we, we go to the axial projection.

2:35

So let's do that.

2:36

Let's see if it'll let me put up three at a time.

2:39

I think it will.

2:42

Hey, there we go.

2:42

Let's get them a little bigger.

2:46

And it looks like we've have something the size

2:48

of a large polo mallet or a wicked or a croquet

2:54

mallet, man, look at the size of that thing.

2:57

It looks like a snowman,

2:59

you know, with a small head.

3:01

Or Casper the Friendly Ghost.

3:04

It's got this peanut shape to it.

3:07

It's between M3 and M4, um, and then

3:12

when you go to the T1, it's kind of gray.

3:15

When you go to the T2 Spineco, now

3:18

on a T2 Spineco, you're supposed to

3:20

have a TE of 90, but not on a PD Spur.

3:24

And this shows our mass to be

3:27

mostly fibrous in character.

3:30

And in the center of it is

3:31

something kind of weird.

3:34

It's this heterogeneous mixed signal intensity,

3:39

and, um, there's really only one diagnosis here.

3:43

Let me just move my pictures out of the way.

3:45

And then, like most things.

3:48

Um, on proton density fat suppression.

3:50

See the TE's 47.

3:52

It's somewhat white, but it is

3:54

not white, like a ganglion.

3:57

It's not white, like a bursal cyst, and

4:00

you go back to the T2 to characterize it,

4:02

and it's actually on the T2 pretty gray.

4:07

So with that position, um, and the

4:10

fact that it's pretty gray, you

4:12

start thinking about fibrous lesions.

4:14

Now there's a whole, a whole

4:16

laundry list of fibrous lesions.

4:18

There's juvenile aponeurotic fibroma.

4:21

Well, he's not a juvenile, he's 81.

4:24

There's foreign body granulomatous

4:26

reactions with surrounding fibrosis.

4:30

Well, it didn't come.

4:31

It didn't come from the skin.

4:33

There's plantar fibromatosis.

4:36

It didn't arise from the, from

4:38

the plantar fibrous tissue.

4:41

There is solitary collagenous or

4:44

simple fibroma, which are tumors.

4:47

Um, I suppose, you

4:49

could bring that up in your head.

4:51

I wouldn't put it in the report,

4:53

at least as you're sifting through

4:55

your, your differential diagnosis.

4:58

One of the sarcomas that likes

5:00

the foot is fibrosarcoma.

5:02

Another foot-loving sarcoma

5:05

is the synovial sarcoma.

5:07

Now, were this to be a synovial

5:10

sarcoma, even though it is big, it is.

5:12

It's totally respecting the toes,

5:15

just simply pushing them apart.

5:17

And then this thing you're looking at in

5:19

the middle is the disorganization

5:24

and irregularity of the nerve.

5:26

That's right.

5:27

You are looking at an interdigital

5:29

nerve, which normally you do not see.

5:34

It's about this size right here.

5:36

That would be the size of a normal

5:38

nerve, and I'll blow it up for you.

5:41

And that's just not a normal nerve.

5:44

Look how big it is.

5:45

Now, why is some of it bright,

5:47

and some of it, uh, sort of gray?

5:50

Because nerves can do one of two things.

5:52

They can either swell or they can have

5:54

paradoxical fibrosis within the, uh,

5:57

the interneural structures and, um, the

6:01

subneural units, or you can have both.

6:04

And that's what's happened here.

6:05

You have both.

6:06

You have some, uh, proteinaceous, uh, fluid

6:09

accumulating within the, uh, epineurium.

6:13

There is an epineurium that contains all this.

6:15

And then you have the fibrous

6:17

disorganization in the middle.

6:19

And then surrounding that, you've got a large

6:23

fibrous inflammatory reaction, which is a

6:26

result of friction, uh, entrapment neuropathy.

6:31

This is an entrapment neuropathy.

6:33

So what are some others?

6:34

Radial tunnel syndrome, cubital tunnel syndrome,

6:38

tarsal tunnel syndrome, dorsal tarsal tunnel

6:42

syndrome, the syndrome of Frosch's arcade, the

6:45

syndrome of the pronator teres, Cubital tunnel.

6:49

Uh, there's a whole laundry list.

6:52

Miralgia Parasitica, uh, Chiralgia Parasitica.

6:55

And here we have, uh, this one,

6:58

which is the Morton's Neuroma.

7:01

It is misnamed, you know, it's not a true neuroma.

7:03

A neuroma is a tumor, and you can

7:08

have various types of neuromas.

7:09

You could have schwannomas, you could

7:11

have neurofibromas, and schwannomas

7:14

previously known as neurolemomas.

7:17

And it's none of those.

7:18

It is.

7:19

It's not even a tumor.

7:21

It is a perineural friction

7:23

induced entrapment neuropathy.

7:25

That's the mother of all Morton's neuromas.

7:30

So you've got the inflammatory reaction by itself.

7:35

It forms this peanut shape.

7:36

Characteristically, it's a little narrower

7:38

dorsally because the compartment is thinner.

7:41

It is wider along its plantar aspect.

7:44

It's got this central area of neural hypertrophy.

7:49

It contains fibrous tissue and cystic tissue.

7:53

Now, some of you are probably wondering, well,

7:55

what might this look like on a contrast MR?

8:00

And it's pretty weird looking, to be honest.

8:03

Here it is.

8:06

And you can see all the fibroinflammatory

8:08

reaction, and that central sort of cystic

8:13

degeneration and fibrous change in

8:16

the nerve itself is not enhancing.

8:20

So it is the perineural tissues that do most

8:23

of the enhancement, and it gives you sort of

8:25

this cold center right there in the middle.

8:28

It looks a little bit like a star.

8:32

Granted, this portion of the star is longer than

8:34

that portion, but those constellation of findings

8:37

between either M2 and M3, or in this

8:40

case, M3 and M4, very typical of Morton's

8:46

neuroma, the right enhancement pattern, the right

8:48

signal pattern, the right, maybe not the perfect

8:51

age, usually a high heel-wearing woman.

8:55

This is a slightly older man.

8:57

The position is just great, and you hardly

9:00

ever get them between M1 and M2 because of

9:03

the arrangement of the digital nerve, and you

9:05

hardly ever get them between M4 and M5, again,

9:09

because of the arrangement of the digital nerve.

9:12

So the diagnosis is Morton's neuroma,

9:16

otherwise known as perineural fibrosis,

9:18

secondary to entrapment neuropathy.