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The next entity we will talk about

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are the four gut duplication cysts.

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This encompasses bronchogenic cysts, enteric cysts,

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and neuro enteric cysts,

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which all probably have a common origin

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and is likely related to abnormal budding of the ventral

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for gut early and gestation between the 26th and 40th days.

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These can be associated

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with additional congenital lung malformations such

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as congenital lobar over inflation

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or bronchopulmonary sequestration.

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Today we'll talk about the bronchogenic

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and the enteric cysts.

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I will not show examples of the neuro enteric cysts,

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but just know if that's on your differential.

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Evaluate for whether the lesion extends towards the spinal

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canal to suggest a neuro enter cyst.

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The first case I'll show you is a CT scan of a patient.

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We have contrast enhanced axial coronal and sagittal images.

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We'll start with the axial images.

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You scroll into the middle of the chest, you will see

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along the right posterior heart border.

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Adjacent to the esophagus is this

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hypo attenuating structure that looks to be fluid filled.

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It does not appear to extend into the spine

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to suggest a neuro enteric cyst.

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And so when you see fluid-filled cystic structures such

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as these in the mediastinum,

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your top two considerations are going

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to be an esophageal enteric duplication cyst

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or a bronchogenic cyst,

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and frequently can be difficult

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to distinguish between the two.

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Although given its proximity to the esophagus in this case,

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I would be slightly more suspicious for that.

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We can also see on the coronal image,

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this is normal thymus in this patient patient,

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and as we scroll through, we see along that right margin,

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that cystic structure that doesn't seem to be

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viewing too much

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besides just sitting there, it's not causing any trouble.

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And then on the sagittal,

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we can again see it here posteriorly.

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These are usually resected when they are found,

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even though they can be incidental findings sometimes

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because they're at risk for subsequent infection

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or very rarely malignant degeneration.

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The next case starts with a CT scan.

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I'm showing here the axial soft tissue contrast enhanced

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images where we see a large cystic structure on the left

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side as opposed to the right side on the other patient.

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And as we scroll through, we can see that it's fairly large

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and as we go through more inferiorly,

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we see an additional cystic focus here

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with some post obstructive ectasis.

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On the coronal images, again, we see that dominant cyst

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near the left hilum

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and then additional cystic components a little bit

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lower and post obstructive

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Atelectasis.

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So although this has features very similar

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to the foregut duplication cyst

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or the enteric duplication cyst

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that we saw in the first case, again,

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this is on the left side,

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so it's farther away from the esophagus, which is over here.

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And while that doesn't completely exclude that it can't be

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an enteric duplication cyst,

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it puts bronchogenic cyst a little bit higher on the list.

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This patient went on to have an upper GI study

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because the clinicians wanted to ensure

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that there was no communication between the lumen

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of the esophagus and this cystic structure we can see here

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as the patient drinks contrast, it goes down

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to the stomach without communication

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into the cystic structure.

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It is important to note

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however, that you can have enteric duplication cysts

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that do not communicate with the lumen

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of the digestive tract.

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So the fact that there's no communication here does not

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completely rule out an enteric duplication cyst,

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but it is still helpful to know clinically in this case.

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This did turn out to be a bronchogenic cyst at pathology.

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And here's another case of a baby

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that had a chest radiograph, uh,

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for acute respiratory symptoms

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when they were a few months old.

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And we can see on this frontal image

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this rounded opacity in the right hilar region.

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And we can also see it somewhat anteriorly on

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the lateral view.

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At the time of interpretation, it was thought

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that perhaps this was related

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to the acute respiratory illness

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and might have represented either around pneumonia

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or lymphadenopathy.

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This patient recovered from their acute illness

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and we did not see them again

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until they were about five years old,

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at which time they returned again

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for acute respiratory symptoms and had a chest radiograph.

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And we see that that finding has persisted.

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It has not resolved over that time.

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We see this round soft tissue density in the hilar region

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that again can be seen on the lateral as well.

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At this point, it was recognized

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that this was not simply lymphadenopathy,

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but likely some sort of benign lesion

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because it hadn't substantially grown in five years.

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And so this patient went on to have a CT scan.

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This is the coronal soft tissue contrast enhanced sequence

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showing that round opacity

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in the right hilar region now with associated

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post obstructive atelectasis causing elevation

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of the fissure here.

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So this structure has gotten big enough

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that it started compressing on airways,

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causing some ectasis.

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We can also see this on the corresponding axial images.

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Here's our ectasis as a result

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of obstruction from the cystic structure.

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This also turned out to be a bronchogenic cyst

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and this was removed.