0:01

This is an axial T2-weighted image

0:02

in a 14-year-old child

0:04

with neurofibromatosis type 1.

0:06

And we can see some cystic changes in the

0:09

region of the right lentiform nucleus.

0:13

If we go down,

0:14

we see they're originating inferiorly

0:16

and projecting superiorly.

0:18

And we see a similar finding on the left side.

0:24

If we look on this coronal image,

0:28

we can see a more solid component

0:30

of a lesion here and here, medially.

0:35

And anteriorly,

0:36

It all connects to this more

0:40

discrete solid lesion.

0:44

On this sagittal T1 post-contrast image,

0:46

we see post-contrast enhancement within

0:49

this supercellular lesion.

0:51

We're seeing a focal indentation along

0:53

the superior aspect of the lesion,

0:55

which is likely due to it being bounded

0:58

by the anterior communicating artery.

1:00

Here are the A2 segments of

1:02

the anterior cerebral artery,

1:03

this part of the lesion is bowing up superiorly here.

1:06

And anterior to the intercerebral arteries,

1:09

this is bowing up superiorly posterior

1:11

to the anterior cerebral arteries.

1:13

And this notch is where it is unable to grow

1:17

superiorly because of the anterior

1:19

communicating artery.

1:21

So,

1:22

we see a separate pituitary gland,

1:27

which can be confirmed

1:31

on other imaging.

1:33

But more than anything,

1:36

we also do not see a discrete optic chiasm.

1:40

And one of the things that helps us identify

1:43

what the origin of this lesion is is knowing

1:47

that the patient has neurofibromatosis type 1,

1:49

where we know they have a propensity

1:51

for optic pathway gliomas.

1:53

And the fact that we do not

1:55

see the optic chiasm,

1:56

that this is a chiasmic glioma in the setting

1:59

of neurofibromatosis type 1.

2:01

Now, there's also involvement along

2:04

the optic tracts bilaterally,

2:06

and the portion along the optic tracts

2:08

actually has this cystic enlargement that

2:11

extends pushes superiorly to the inferior

2:13

aspect of the lentiform nuclei bilaterally.

2:16

So if we look at the orbital segment

2:20

of the optic nerves,

2:22

we're actually not seeing any

2:24

definite involvement.

2:25

So, this is almost purely chiasmatic

2:29

and optic tract involvement.

2:31

So while optic pathway gliomas,

2:34

we often think of the optic nerve involvement,

2:36

in particular the orbital segment

2:38

of the optic nerve.

2:39

It can be anywhere along this optic pathway,

2:42

including, as seen in this case,

2:43

the optic chiasm and optic tracts.