0:00

So let's talk about perio, lymphatic nodules.

0:03

Now again, so these are nodules which are gonna live

0:05

along the lymphatics.

0:07

And so here again is my diagram.

0:09

So these nodules are gonna be along the interloper, septa,

0:11

subpleural lung, sometimes central lo core structure

0:14

and along the bronchovascular tree.

0:17

And so as opposed to random nodules

0:18

where they're like really all over the place, like tropic,

0:21

these perilymphatic nodules tend to cluster.

0:24

Let's just show you example here.

0:26

So here's example

0:27

of these nodules along the intra lo receptor subpleural lung

0:30

along the bronchovascular tree.

0:31

But notice on this axial slice nodules in the more center

0:35

mid portion of the lung from an

0:37

anterior posterior direction.

0:38

There's a lot of nodules here,

0:39

but anteriorly especially right here, kind more peripherally

0:43

and laterally, there are almost no nodules.

0:45

And then posterior, there's just a few nodules.

0:47

So perilymphatic nodules really like to do this,

0:50

especially sarcoidosis, which is gonna be the first thing

0:53

that you think about when we see perilymphatic nodularity.

0:57

Here's our differential diagnosis for paralympic nodularity,

1:01

but again, most of the time it's gonna be sarcoidosis,

1:03

whether primary or secondary.

1:05

Remember there are secondary causes of sarcoidosis.

1:08

People act like they know sarcoidosis.

1:10

They're like, oh, that's just sarcoidosis.

1:12

But sarcoidosis is like very esoteric.

1:14

No one really knows what causes sarcoidosis.

1:18

It's probably the same endpoint

1:20

or same phenotype of many different stimuli, which then lead

1:23

to the same imaging morphology

1:25

and same pathological abnormalities that we see.

1:28

And that's why there are both idiopathic sarcoidosis cases

1:31

and secondary sarcoidosis cases.

1:33

But um, bottom line, the more I learn about sarcoidosis,

1:36

the more I realize I don't really understand.

1:38

Sarcoidosis. Very, very interesting.

1:40

One of the secondary causes of sarcoidosis,

1:42

which is well defined from occupational exposure,

1:45

is chronic beryllium disease or borreliosis from.

1:48

So if someone works in aerospace

1:49

or manufacturing of, of certain types of lamps

1:52

or just maybe works in, in a place that uh,

1:55

maybe minds this stuff,

1:57

then obviously you would think about borreliosis.

1:59

But most places don't have a bres

2:01

clinic or beryllium clinic.

2:02

If you do, then obviously it would be something you include

2:04

in differential diagnosis.

2:06

So paralympic nodules, sarcoidosis,

2:08

sarcoidosis, sarcoidosis.

2:10

And every once in a while you just wanna make sure you're

2:12

not dealing with a case of lymphocytic carcinomatosis.

2:15

But usually most of those cases they manifest

2:18

with interocular, septal thickening

2:20

and some associated nodularity along the interlobular septa

2:24

rather than the para lymphatic nodularity being the major

2:27

finding on that CT scan.

2:30

Also, when you have lympho genetic carcinomatosis,

2:33

very commonly they're gonna have other

2:35

manifestations of malignancy.

2:36

You're gonna have like maybe even like a big tumor,

2:38

which is the primary tumor.

2:39

And then you're gonna have adjacent

2:40

lympho, genetic carcinomatosis.

2:42

So it's spreading into lymphatics,

2:43

or we're gonna have like macroscopic nodules within the

2:45

lungs which spread their hematologist

2:47

and now are extending into the interlobular

2:50

septa and the lymphatics.

2:52

So usually it's not a diagnostic conundrum in

2:55

that alternative diagnostic consideration of lympho genetic

2:58

Carcinomatosis.

3:01

So more sarcoidosis here.

3:03

Paralympic nodularity, beautiful example.

3:05

Again, they like the cluster sarcoidosis.

3:07

I don't know why, but beautiful example

3:09

of interocular sepup here.

3:10

Rock blaster tree, visual nodularity, subpleural nodularity,

3:14

just classic sarcoid sarcoidosis likes

3:17

to be mid upper lung preponderant,

3:19

but I certainly have also seen cases

3:20

of basal predominant sarcoidosis.

3:22

It's not as common, but it should not dissuade you from a

3:25

diagnosis sarcoidosis just based on zonal distribution.

3:29

Another example of sarcoidosis with mass like fibrosis here.

3:32

So, so sometimes patients with sarcoidosis can start

3:34

to evolve into a fibrotic pattern.

3:37

And so very commonly you take a mass like morphology.

3:40

And so we see that here on ct. This is just an MRI.

3:42

This is just a vibe sequence with gadolinium contrast.

3:45

So those of you guys who do a lot of cardiac MRI,

3:47

you should probably look at these vibe sequences

3:50

or your T one sequences, uh, carefully,

3:52

especially after contrast.

3:53

'cause I very common with MRI, you're looking

3:56

for an infiltrative abnormality like cardiac sarcoidosis.

3:59

And so if you're looking for cardiac sarcoidosis,

4:01

you should probably look for pulmonary sarcoidosis as well.

4:03

And this patient indeed had pulmonary sarcoidosis

4:05

with very beautiful perilymphatic distribution.

4:09

Here's the case of lympho genetic SP tumor.

4:11

You see how this just looks different.

4:12

So what, what's the diva of this CT scan here?

4:15

You know, what's who? Who is the star of the show here?

4:17

It's not nodularity is it?

4:19

If you look carefully, it's gonna be the

4:21

interlobular septal thickening.

4:23

Sure, there's nodularity there superimposed on there.

4:26

And sure it's perilymphatic

4:28

because it's along the Interlobular septa.

4:30

But the major finding here is that

4:32

of interlobular septal thickening with concomitants.

4:35

That's the secondary finding of interlobular,

4:39

lymphatic nodularity.

4:41

But this patient has like ular pleural fusions bilaterally.

4:44

The patient history of malignancy.

4:45

I mean, come on, no one would call this sarcoidosis.

4:47

I think anyone who has any

4:50

clinical experience at all in terms of diagnostic chest ct,

4:53

the first thing that you'd be worried about,

4:54

the first thing you would exclude would be

4:56

that this is some sort of bad limited carcinomatosis.

4:59

Maybe a lymphoma or some sort of odd leukemic infiltration

5:02

or other inflammatory infiltrative abnormality.

5:05

So yeah, this is not sarcoidosis, chronic brelin disease.

5:09

I just wanna bring this up. And so sometimes

5:11

these can look a little different.

5:13

And so if we look at the CT scan very, very quickly,

5:16

we might say, oh, there's just ground lass

5:18

opacity all throughout the lungs.

5:19

But you know that it's not brown lass opacity,

5:22

it's more this fine granularity,

5:24

which actually is clustering along fissures along the

5:26

bronchovascular tree

5:27

and in some areas along the subpleural lung.

5:29

So this is a patient actually

5:30

with chronic beryllium disease,

5:32

but with a fine perilymphatic, nodularity.