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Hey everyone, it's Mark, and we're gonna keep going

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here on our imaging, uh, series of the, uh, lungs.

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Cystic (Curved Reticular) pattern will be the topic of

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this session and in our cardiac morphology approach.

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Again, we're just looking for ways to describe

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the abnormalities we see, especially in

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radiographs, but on CT too, and then kind of deduce

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how and what pathology is there

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and what is the possible etiology.

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So cystic or curved reticular

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pattern is what we'll talk about.

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So what these are—you'll notice that

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the lungs look busy, and you'll look, and it's

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like it's a reticulation, which, again, are

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lines that don't branch, but they're curved.

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They almost look like commas.

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So you see a number of different commas

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forming, and when you see these commas, you can

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see some commas up there or curved reticular

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opacities.

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You think of three different

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pathologies: bronchiectasis,

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emphysema—especially bullous emphysema.

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On the radiograph, you can't really see

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the centrilobular too well, and cysts.

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Okay.

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And cysts—there's the differential for cysts.

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It's a little long, but not too bad,

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and we will talk a little bit about it.

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So those are the three pathologies.

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So curved reticular opacities, mostly perihilar.

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In this patient with hyperinflated lungs, you

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can see there are fluid levels here, and some of

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these curved reticular opacities look elongated.

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When you start to see so many

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of these curved reticular opacities, especially centrally,

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and with fluid levels, it starts to make you think about

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bronchiectasis, and in this case, it's cystic fibrosis.

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The reason they're hyperinflated is 'cause they

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also have advanced constrictive bronchiolitis,

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which is a topic for another session.

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Bronchiectasis—when you approach the

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differential, you kind of look and see, is it

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localized, or does it seem bilateral, widespread?

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If it's bilateral and widespread, you think about

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immune deficiencies or congenital abnormalities.

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Cystic fibrosis is a nice example, and

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you can see how they form these almost

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clustered cysts, but they're not really cysts.

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It's just cystic air bronchiectasis.

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This person has an IgG deficiency, and they

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have recurrent infections and bronchiectasis.

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Another patient.

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And you can see this clustered—almost looks like

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cysts—except they communicate with the bronchi.

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This clustered appearance, again,

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is suggestive of bronchiectasis.

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There are air-fluid levels, and in this case, this

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distribution between like the fourth and eighth

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segmental bronchi is very characteristic of

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something called Williams-Campbell syndrome, which

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is a congenital, uh, cartilaginous abnormality.

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When bronchiectasis is more localized, like here,

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then you start thinking, well, they probably had

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some sort of infection there, got damaged, and then

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it gets recurrently infected and worsens that way.

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So you don't tend to think more of the immune, uh,

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as much anyway.

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Or the congenital.

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Now, quick thing—uh, signet ring sign is often

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taught as the sign for bronchiectasis. Radiologists

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know, or, uh, jewelry—that is not correct.

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Signet ring is this.

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It's actually the solitaire ring sign

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that looks like a solitaire ring.

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So just as a little myth thing, if

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you want to have fun and read out.

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A 30-year-old male, and you take a look. They

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have a chest tube 'cause they had a pneumothorax.

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And you look in the upper lobes,

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and you're like, oh, wait a minute.

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Curved reticular opacities, commas.

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They don't look too central.

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They have an upper lobe distribution.

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These are probably cysts.

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Cysts in the upper lobes, no

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real ground-glass that I see.

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We'll do a CT—lots of these cysts around,

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kind of, uh, irregularly shaped cysts.

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This is fairly characteristic for Langerhans

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cell histiocytosis.

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I guess you could consider a sort of chronic

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Pneumocystis if he was HIV-positive, but probably not. Now,

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how do you tell a cyst from emphysema on CT?

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It can sometimes be tough, but cysts have

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walls usually, and they have nothing in 'em.

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Emphysema doesn't really have much for walls, and

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they have dots and lines in 'em—dots and lines.

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So you shouldn't have dots and lines in a cyst, right?

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A cyst should be empty. So emphysema,

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no walls, or, you know, maybe something

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that looks like a wall on part of it.

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And then it has these dots, though—dots and lines.

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That's the key.

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Now, the only real emphysema you can see directly—

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you can see indirect signs of very advanced centrilobular

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emphysema—but directly, it's bullous emphysema.

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And it looks—'cause it compresses the, the

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lung—so part of it, you can see that curved

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reticular kind of opacity or the commas, and

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that's characteristic of bullous emphysema.

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Usually, it'll be upper lobe,

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so-called vanishing lung syndrome.

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Another patient—they have curved reticular opacities.

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You can see them there, commas, but there's also

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associated ground glass that's in the perihilar and

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upper lobes, maybe even a little early consolidation

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here. But mid to upper lobes, no history. In this

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case, it's upper lobe cysts, ground glass, chronic

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ground glass, or—I mean—acute ground glass.

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We would look on our card, and that comes out, and this

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is Pneumocystis pneumonia in a patient with AIDS.

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Another patient on CT—recurrent

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pneumothoraces, family history, multiple cysts.

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This kind of looks like it could

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be emphysema, but these are cysts.

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These are all cysts here.

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Cysts.

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This is actually something

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called Birt-Hogg-Dubé Syndrome.

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It's a genetic

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defect where they develop lung cysts,

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multiple pneumothoraces, and have various

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sorts of skin abnormalities, and

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small nodules, pustules, and things.

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A 33-year-old with SG runs lots of ground glass, some

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pulmonary hypertension, but look a little closer.

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When you see this, you see these curved reticular

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opacities or these commas—that indicates that

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there's something else underlying. Now, maybe

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this is just diffuse ground glass with emphysema.

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And the emphysema is outlined because of the

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ground glass, or this is ground glass with cysts.

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And so, you know, we would do a CT

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scan here to try to figure that out.

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And when you look, you're

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like, oh yeah, these are cysts.

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These are definitely cysts.

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No dots, no lines, randomly

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distributed chronic ground glass cysts.

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Sjogren's. This is LIP—lymphocytic

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interstitial pneumonitis.

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Uh, it's not LAM most likely because

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LAM does not give you ground glass.

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One more patient.

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Lots of ground glass.

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But notice where these cysts are.

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They're in the perihilar region, and

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they're sort of extending out along the

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hilum and of bronchovascular distribution.

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Now, you'll see this in smokers, and it looks like

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there, you know, will be centrilobular emphysema.

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And this often gets called emphysema.

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But if you look a little closer, you

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will see that these do not have dots.

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These are actually cysts.

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So this is something

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called desquamative interstitial pneumonitis,

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DIP. And DIP can form these cysts, and they

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usually form 'em in the perihilar region.

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Sometimes they can get out a little farther,

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and you may see associated emphysema too.

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So when I see this, I usually go, "Hey, there's

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some emphysema and perihilar cysts consistent

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with smoking-related reactions of DIP."

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So, summary: curved, reticular opacity or

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cystic disease—it's comma-shaped, and it

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reflects one of three different pathologies:

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bronchiectasis, cysts, or emphysema.

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Remember, cysts tend to have walls and have

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no dots or lines in the center or within them,

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as opposed to emphysema. Assess

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the distribution of the cysts.

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Are they perihilar?

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Are they random?

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Are they upper lobe?

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And is there any associated ground glass

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that will help you narrow your differential?

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Central or localized distribution more

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often suggests that it'll be bronchiectasis.

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Okay, with that, thank you so much.