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Hey everybody, it's Mark again, and we're

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gonna continue our Mastery Series on pattern

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recognition, and we're gonna go through

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cardiopulmonary imaging of multiple nodules.

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Multiple nodules. Now,

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what are we gonna talk about?

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The objective is to discuss the importance of the

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distribution and size of these pulmonary nodules and

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look at that distribution based on the radiograph,

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but as well on thin section CT, which brings into

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the concept of the secondary pulmonary lobule.

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And then we'll also kind of discuss how.

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Nodules that are of a similar size are

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usually gonna be a different disease

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process than nodules that vary in size.

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These will be your morphology clues.

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So going back to what we've been doing as we go

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through these patterns, we're gonna focus on nodular,

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cavitary and non-cavitary, as well as the budding

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tree opacities or the terminal bronchial filling.

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So nodules, when you kind of look at multiple nodules,

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the differential really is sort of metastasis.

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Pretty much any tumor and metastases tend to

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vary in size, so the nodules vary in size

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versus the disseminated granulomatous diseases.

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The infectious causes like TB, fungal,

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and sarcoidosis, and non-infectious, and

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these nodules tend to be similar in size.

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Other nodules that are related to

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inhalational or lymphatic diseases tend to

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have a bit of an upper lobe predominance.

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And the last one, the subset

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or the so-called ary nodules.

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And ary nodules really refer to nodules that

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are very small, less than three millimeters.

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So first of all, pulmonary nodules.

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Well, how do you kill a pulmonary

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nodule from a vessel on end?

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Well, when there's multiple like

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that, that's probably a nodule.

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But if you have like only a couple, is this

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a pulmonary vessel or is that a nodule?

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Well, there is a vessel of the same caliber

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heading right towards it, so it's likely that

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that is actually gonna be a vessel seen on N

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as opposed to this nodule here where there's

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no pulmonary vessel of the same size coming.

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So that's one way to tell is that if there is a vessel

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of the similar caliber heading towards it, that's

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probably going to be a vessel on end and not a nodule.

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Multiple pulmonary nodules.

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The distribution of these is really helpful and in

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this patient, that's clearly upper lobe, and there's

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also evidence of hilar retraction, you know, like an

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old man's pants in Florida, very high belt kind of

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pulled up, that tells you that there's chronic scarring

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in the upper lobes with these pulmonary nodules.

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And then on the card, you'd look at, you know,

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multiple nodules, upper lobe distributions.

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Kind of see which diseases are in both, and this

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one was sarcoid, but this one looks very different.

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There are multiple pulmonary nodules.

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They're well-defined, but they vary in

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size and they're randomly distributed.

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Oof.

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What would that be?

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Well, that's gonna be metastases

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most likely until proven otherwise.

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Again, granulomas tend to be similar in size.

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So when you see these random nodules,

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especially well-defined and varying

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in size, you favor metastatic disease.

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So these are the miliary nodules.

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These are millet seeds, by the way, that

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a radiologist took a radiograph for me.

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'Cause I didn't know what millet seeds look like.

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And I was like, oh, wow, that's aptly made.

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Miliary nodules look like they're very, very tiny.

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At first you may think, oh, they're ground glass,

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but when you look a little closer, it's sort of

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like looking at the sky at night, clear sky, and

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you see a few stars and you keep staring, and

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then there's just a plethora of stars, and that's

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what we're seeing here are these multiple kind

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of similar size small nodules all throughout.

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That just refers to miliary.

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If they're similar in size like this one, you

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usually think of disseminated granulomatous disease.

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In this case, it was miliary histoplasmosis,

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and in this case, miliary sarcoidosis.

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So let's shift now.

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Distribution based on the secondary pulmonary lobes.

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So when you're looking at thin section CTs, this

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becomes a very important reference on distribution.

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This is a secondary pulmonary lobule, the

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smallest functional unit of the lung, and

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these are the interlobular septations where

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they have pulmonary veins and lymphatics.

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Then you have your terminal bronchioles here, and

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the pulmonary artery and arterioles and any in

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between are the alveoli and the, uh, parenchyma.

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So that's your secondary pulmonary lobule.

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Nodules based on the secondary pulmonary

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lobule come in three major flavors.

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They got perilymphatic, random, and central lobular.

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Perilymphatic will usually be along the septum.

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Central lobular is usually somewhere in that

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center point of the terminal bronchial or pulmonary

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arterioles, and those come in two different forms.

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Terminal bronchial filling or the so-called budding

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tree, an ill-defined ground glass nodularity in

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the central lobular, which is usually an inhalational

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problem where something gets inhaled and induces

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an inflammatory reaction in the respiratory

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bronchioles, this is what they look like. Random is

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everywhere.

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It's the pleura, the fissure, parenchyma.

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There might be some along in the perilymphatic area.

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Then you get the perilymphatic, which

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the nodules really kind of line up and

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are beaded, and they're along the bronchi.

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They're along the fissure.

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They may be along the pleura, they're

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along the pulmonary arteries and veins.

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Okay, where the lymphatics live.

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And then the last one is the central lobular, and the

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key here is that it spares the pleura and the fissures,

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central lobular spares the pleura and the fissure.

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So let's go with random.

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You have a random distribution of pulmonary

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nodules. If they vary in size, you consider

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metastasis until proven otherwise.

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And if they're similar in size, you

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should consider granulomatous disease first.

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30-year-old non-smoking woman.

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She has a history of poorly responsive

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asthma, which is not asthma, right?

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Somebody made that up.

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It's something else.

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And you can see all of these pulmonary

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nodules, and they're very random.

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They're along the fissure, the central lobular.

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There's some subpleural, and they're

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varying in size, and they're similar.

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So this is actually very sarcoid.

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She actually had sarcoid.

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Two patients with miliary nodules and in the random

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distribution, but these are all similar in size.

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You would think granulomas, and it was

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miliary histoplasmosis, tuberculosis,

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or coccidioidomycosis could have a similar appearance.

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This patient has nodules that vary in size,

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so even though they're miliary, they do

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vary in size, and those are metastatic metastases.

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Now central lobular nodules,

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again, two types: ill-defined.

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Ground glass and the budding tree appearance.

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They spare the pleura and spare

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the fissure if they're ill-defined.

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Ground glass, you usually think of extrinsic

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allergic alveolitis if they're not a smoker

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and R-B-I-L-D, respiratory bronchiolitis,

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interstitial lung disease if they're a smoker.

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This also can occur with occupational exposure.

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The budding tree is usually going to be some sort of active

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inflammatory process within the terminal bronchial.

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So this is an example of the smudgy ground glass

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nodularity, central lobular sparing the pleura.

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This is consistent with an inhalational

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problem, and this patient was a non-smoker,

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and this was extrinsic allergic alveolitis.

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It turns out smokers

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generally don't get extrinsic allergic uveitis.

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'Cause smoking is actually an

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immunosuppressant in the lung.

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So if they're a smoker, you'd say,

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well, that's probably our R-B-I-L-D.

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This is an example of the budding tree appearance.

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You can see how they look like the jacks,

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you know, the ball and jacks when, well, you.

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The younger kids won't know what I'm talking

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about, but, and it spares the pleura, and

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this is an active inflammatory process.

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Usually a broncho pneumonia, mycoplasma

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viral infection kind of thing right here.

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And this is usually seen in the setting

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of active inflammatory disease.

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BMT patient, bilateral budding

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tree, pretty extensive spares.

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The pleura, this is influenza.

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RSV, parainfluenza could have a similar appearance.

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Note, COVID doesn't look like this 'cause

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COVID is a virus that infects the alveolar

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epithelium and induces a direct alveolar damage.

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So this would not be consistent with COVID.

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Now, perilymphatic nodules are multiple nodules that

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are beaded and lined up along the areas where there are

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lymphatics, and there are two major things that occur.

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Sarcoid and lymphatic spread of tumor.

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Those are the two.

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Sarcoid tends to be more central and

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bronchovascular, radiating out with the nodules

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lined up, and lymphatic spread of tumor

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usually, not always, tends to have more peripheral

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septal thickening with associated nodularity.

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So this would be the example.

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You can see these nodules, they're

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radiating along the fissure.

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They're in the subpleural and definitely radiating

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out from the hilum, the so-called bronchovascular.

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This is different.

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You can see their septal thickening, but

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there's associated nodularity, and you

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can tell that these nodules vary in size,

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and look at their beaded appearance.

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Another patient, septal thickening, beaded appearance,

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lymphatic spread of tumor here and here, sarcoid

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here, just based sort of on that distribution and size.

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Lymph spread of tumor.

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When you do see it, tends to be adenocarcinoma.

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Pick the most common for the

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patient's age and sex or lymphoma.

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And you can see this perilymphatic nodularity if you

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look real carefully, and you have a lot of coffee.

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If you look at the fissures on these

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radiographs and you see that beaded appearance

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along the fissure, that suggests to you

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that this is a perilymphatic distribution.

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This patient had sarcoidosis, and this patient, which

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had the septal thickening, slightly subtle beaded,

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nodular appearance, some nodules and a mass right here

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in the right upper lobe, lymphatic spread of tumor.

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So we'll finish with cavitary nodules and masses.

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These tend to either be infectious or neoplastic.

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Other causes that are rare are vasculitis,

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and trauma with traumatic lung cysts, but

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we'll focus mainly on infections and neoplasms.

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The big thing you want to look at a

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cavitary is the inner wall.

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Is it smooth?

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If it's smooth, it's most likely an infectious cause.

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If it's irregular and nodular, that's

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probably gonna be a cavitating tumor.

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So a patient has thin-walled, multiple

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thin cavitary nodules bilaterally, and

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it is very thin with fluid levels.

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They're randomly distributed, varying in size.

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This patient had a fever and is an IV drug abuser.

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Septic emboli, differential septic emboli.

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So these two patients both have cavities.

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This is a cavitary consolidation,

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smooth inner wall, likely infectious.

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That was coccidioidomycosis.

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Mycosis.

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This one, not so good.

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You can see the nodular irregular appearance.

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That is a cavitary tumor.

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That is a cavitary squamous cell lung cancer.

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So in summary, multiple pulmonary nodules

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similar in size, think granulomatous,

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varying in size, think metastatic on a CT.

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Try to deduce the best of your ability where

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it is relative to the secondary pulmonary lobe.

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And remember that central lobular spares the

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fissures and the pleura, cavitary nodules and masses.

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Look at the inner wall.

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Thank you so much, and I hope that was helpful.