0:00

So let's look at our next case. This is case two. This is

0:06

a male in his 70s and 18 months prior to this,

0:13

he had had a wedge resection for an early non small cell lung

0:18

cancer in his right lower lobe. And this is the CT.

0:26

And this is just a routine follow up for his cancer.

0:31

Just come back up a little more. Alright, so can we have the

0:41

next question? So question two, you can see a split pleura sign. Does

0:47

this mean there is an empyema? Yes or no?

0:51

Good, so about 20% thought yes, it does, and 80% thought no.

0:56

And that's right. So the split... The nos have it right.

1:01

So the split pleura sign is classically used to differentiate a lung abscess

1:05

from an empyema. But I think oftentimes when we see this enhancing pleura,

1:10

it makes us nervous that we're definitely seeing an empyema. But we can

1:15

get this smooth enhancing pleura in just a chronic pleuritis. And that's

1:21

what we're dealing with here. So the patient had a procedure.

1:25

Often this pleuritis will develop after cardiac surgery, for example, if

1:32

there's a hemothorax or after trauma or after

1:36

any other surgery when there's some irritation in the pleural space.

1:40

And there's a little bit of fibrotic reaction along

1:46

the pleura and fluid is not going to drain

1:50

properly. So as fluid passes through the lungs, it goes through the lungs

1:54

and interstitium of the lungs and then out through the pleural space and

1:57

gets resorbed by these tiny little holes in the pleura. And when there's

2:02

a little bit of fibrotic reaction, it can't resorb. So we end up

2:06

with a little bit of an effusion and a thin enhancing pleural surface. And

2:12

it can be more conspicuous than this. This is quite thin.

2:17

It can be thicker than this, if there's been chronic inflammation or multiple

2:22

episodes of inflammation, or if it's been attempted to be drained a lot.

2:28

Now, what goes along with that is this area of folded lung. And

2:32

so this is a contrast scan, which is really helpful, as I said

2:35

before, atelectatic lung enhances really brightly and uniformly. And this

2:42

lung is enhancing brightly and uniformly. There are no patchy areas of hypo

2:47

enhancement making me think that there's cancer in there or that there's

2:51

pneumonia in there. It just looks like a gland enhancing lung. And

2:57

I think we've all heard of the comet tail sign where there is

3:02

volume loss and the vessels start to twist around and aim towards the pleura,

3:11

and it looks a little bit like a comet tail coming around,

3:16

which I think you can appreciate here. It's a little bit of a noisy image,

3:19

that's a bit better. So the comet tail sign is another one of

3:23

the findings we see with a rounded atelectasis. Another term for rounded

3:32

atelectasis is actually folded lung, which I kind of like, because you can

3:35

see that the lung is really folded in on itself. And what's happened

3:39

here just as there's been inflammation and a fibrotic reaction along the

3:43

visceral pleura, the parietal pleura has the same. And so when lung tries

3:48

to re expand, it can't, because it's trapped by this

3:52

visceral pleura that's gotten all thick and won't expand normally.

3:59

Normally, it should expand out to the edge of the pleural space.

4:04

And so I find sagittals especially nice to look at this volume loss.

4:09

You can see how the oblique fissure here instead of being right up

4:15

here as it should, it's really curved down. So this volume loss and

4:19

nicely enhancing lung makes me very confident that this is

4:24

simply rounded atelectasis related to chronic pleuritis. I'm not worried

4:30

that there's infection, and I'm not worried that this represents a recurrence

4:36

of the cancer. I think this also shows how helpful contrast really is

4:41

in this setting and without contrast, I think we would be maybe a

4:45

little bit less certain. We can still use these findings of volume loss

4:49

and the comet tail, and you might perceive the pleura to be a

4:53

little bit thick, but I think contrast really helps in the setting

4:59

to make us more confident that that's all we're dealing with.

5:04

Now what's wrong with saying you know, "Oh, but I can't exclude pneumonia"

5:07

or "I can't exclude a recurrence." I mean if you say "I can't

5:13

exclude a recurrence" probably what will happen is they'll get a pet CT

5:18

which you know that's expensive, you would expect it to be negative though

5:21

so that would be reassuring. So, that could be helpful in that sense.

5:27

If you say I can't exclude pneumonia, they may try to tap the

5:31

fluid, which you know the problem with that is that usually this lung

5:37

does not expand out to the pleural surface. And so end up with

5:42

sort of an ex vacuo appearance, and it's difficult to get the chest

5:47

tube out. The patient may spend quite a few days in the hospital

5:51

with their chest tube unable to get it removed.

5:55

And then eventually, because the lung doesn't re expand, it just simply

5:59

fills up with fluid again. Certainly by introducing drains and so forth,

6:06

you're actually increasing the chance that the patient may develop an infection.

6:11

So I think it's important not to add phrases like, "Oh,

6:15

I can't exclude infection," and "I can't exclude cancer," when not seeing

6:20

any positive signs that either of those exist. While we are seeing a

6:25

lot of positive signs that this is simply a pleuritis with rounded atelectasis.

6:30

So, if I was reporting this, that's how I'd report it, and I

6:34

would not put any caveats for infection or recurrence

6:40

in this case.