0:00

Dr. P here with a 62-year-old man complaining of

0:01

3 00:00:03,639 --> 00:00:08,119 pain when walking and instability, and I don't

0:08

think that's really going to be the focal point

0:10

of this review, even though he does have a

0:13

wavy, detached anterior talofibular ligament,

0:17

and all kinds of other findings including soft

0:20

tissue swelling and ankle effusion and so on.

0:24

The main finding that I want to

0:25

illustrate here is, what in the

0:27

world is going on in this calcaneus?

0:31

It looks like you've got a runway right

0:32

up the center of the calcaneus and

0:35

these very weird areas of high signal

0:38

intensity on the water-weighted image.

0:40

By the way, this is a low-field

0:42

scanner doing just a fine job.

0:44

And then you've got some very dark signal

0:47

intensities on some of the other sequences.

0:50

Now if we look at what sequences we're

0:51

dealing with, we're dealing with a

0:53

proton density non-fat suppression in

0:55

the middle and a T2 on the far right.

1:00

I think it would be appropriate at this juncture

1:02

to call up a T1 sagittal, so let's do that.

1:05

Here comes our T1 sagittal, and perhaps that

1:08

will shed some light on what's going on.

1:11

And when we do, I think all of you

1:14

are struck by the massive fat signal

1:18

intensity that dominates the entire image.

1:22

This entire area is not just

1:25

marrow, it's too homogeneous.

1:27

I mean, look at the fibula.

1:29

You know, it's got a little speckling to it,

1:31

it's got a little architecture to it, and when

1:34

you look at this lesion, it has no architecture

1:36

whatsoever other than these very weird septations.

1:40

And then we also saw that septation

1:41

running down the middle in the axial.

1:43

We have more of them.

1:45

So this is a case where the

1:47

MR really solves a problem.

1:49

Because the main differential diagnosis

1:51

here is a unicameral bone cyst of the heel,

1:53

which can fracture and can require the

1:57

placement of bone chips or bone grafts.

2:00

Whereas this lesion, the calcaneal lipoma, does

2:04

not. We leave these alone, they do cause pain.

2:07

And the reason they cause

2:08

pain is they may infarct.

2:10

And when they infarct, you get these cystic areas

2:14

that may calcify or ossify, much like we see here.

2:19

We saw it in the axial projection.

2:20

Let's go back to it for a minute.

2:22

We'll put two up.

2:23

We'll put our water-weighted sequence up.

2:25

Look at these calcifications back here, which

2:28

are better seen on the proton density image.

2:31

And again, some low signal

2:32

intensity foci on the axial T2.

2:36

And within that calcification, occasionally,

2:39

you'll even get cystic degeneration

2:41

inside, which is kind of strange.

2:44

So you'll have a cystic area, you've got your

2:46

calcaneal lipoma, then within your calcaneal

2:49

lipoma, you may have a cystic area. Then, within

2:53

that cystic area, you may have some calcification.

2:58

And then, within that calcification, you may

3:00

actually have another cystic area inside.

3:03

And this gives rise to what's known

3:05

as the Leisegang ring-like appearance,

3:07

where you have a series of concentric

3:09

rings associated with this lesion.

3:13

Another pattern of calcification is known as

3:15

the birch broom pattern of calcification in

3:17

which it looks like the edges of a birch broom

3:20

in the intramedullary space of the calcaneus.

3:24

There's no sex predilection for this lesion.

3:27

There's no age predilection for this lesion.

3:30

It is a pathognomonic diagnosis.

3:32

You've got fat in the calcaneus.

3:34

You've got calcium.

3:35

You've got cyst formation.

3:37

Dr. P out.