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This image on the left

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is an MRI of the brain in a 4-year-old child

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with neurofibromatosis type 1.

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We can see in the region of

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the left globus pallidus,

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a rounded area of T2 hyperintense signal.

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This is an area of myelin vacuolization.

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The globus pallidus is a very common place for this.

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Now, notice approximately two years later,

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that's no longer present

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And approximately six years later beyond that,

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it's also not present.

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So, this shows that these areas of myelin

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vacuolization can wax and wane.

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Now if I look a little bit more superiorly,

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we can see that between

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this initial study and the subsequent study,

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this juxtacortical ovoid T2 hyperintense lesion

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arose in the posterior aspect

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of the right middle frontal gyrus.

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We don't know what that is.

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So, how do we characterize it?

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We can see it does not enhance

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on post-contrast imaging.

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It has facilitated diffusion on diffusion

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weighted imaging based upon the

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bright signal on this ADC map.

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These are all features that go against an

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aggressive entity, but nonetheless,

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this is a new sort of cystic appearing,

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juxtacortical lesion that arose.

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So, obviously, we want to be very careful about it.

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We want to describe it,

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and we want to make sure the

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patient gets follow-up.

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Well, several years later,

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it's no longer present.

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So, this is an example of why a new lesion in

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neurofibromatosis type 1 does not

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immediately need to go to surgery,

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does not immediately need to go to biopsy.

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It needs to be described,

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needs to be fully characterized to the best we can.

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It needs follow-up.

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We need to be aware of this,

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which is why we need to make comparisons between

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each study to make sure things aren't

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getting bigger or smaller.

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But just because they get bigger or smaller does

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not mean, in neurofibromatosis type 1,

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they need to immediately go to surgery.

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In a patient without neurofibromatosis type 1,

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new development of a juxtacortical cystic lesion

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is worrisome.

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It may not require going to surgery immediately,

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but usually, this would be something that

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would catch someone's attention.

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in neurofibromatosis type 1, we'll describe it.

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It definitely catches our attention,

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but we can see, by the fact that this goes away,

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it's appropriate in neurofibromatosis type 1

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to be aware, the waxing and waning of these areas

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of myelin vacuolization to not immediately

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jump to surgery for every single lesion.

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So, one additional thing to note in this patient.

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Looking at the sequence of events,

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we see the absence of a cystic lesion to

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the development of a cystic lesion,

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to the resolution of a cystic lesion.

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So in neurofibromatosis type 1,

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we have to just always be on the lookout,

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because there can be lesions all over the place.

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So just on this image,

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we can see in the scalp,

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outside the brain,

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but we try and look at the whole image,

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we see the subcutaneous soft tissues

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in the right parietal region.

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And then on the follow-up image,

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but now on the most recent image,

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look at this thickened soft tissue.

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This is a plexiform neurofibroma

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i the scalp.

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It's external to the skull

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because we can see here,

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this dark line here is the outer table

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cortex of the skull.

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This thinner dark line here is the inner table

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cortex of the skull.

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This thin, bright line here is the marrow

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within the diploic space.

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And this thickening here is

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a plexiform neurofibroma.

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So this is just an example of how,

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in neurofibromatosis type 1,

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it's important to just look at the entire

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study on every single examination,

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because even if you're following up one lesion,

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another abnormality may arise.

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Or in the case of this cystic appearing

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lesion, may actually disappear.