0:00

Dr. P here back with our 72-year-old woman with a known

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3 00:00:04,860 --> 00:00:07,790 greater than 4 centimeter anterior inferior pole left

0:07

renal mass. I'm starting out with two quick images

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from our in-phase out-of-phase Dixon method M Dixon

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method and fat sep series: the fat-only image and the

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water image as part of that subtraction. The fat-only

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image has lots of fat inside, nice and bright, whereas

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the water image shows the lesion to be very dark,

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dropping out, virtually having no signal intensity,

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and the lesion therefore contains macroscopic fat.

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The lesion is consistent with probably one of the

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most commonly encountered benign solid renal tumors,

0:44

known as angiomyolipoma, which occurs in adult women.

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They're now classified as part of the family of

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perivascular epithelioid cell tumors, or PEComas.

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Now AMLs are typically composed of blood

0:59

vessels, so they're vascular, smooth muscle

1:01

components, and mature adipose tissue.

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Most of these are sporadic, but occasionally

1:06

you'll see them in association

1:08

with tuberous sclerosis complex.

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An example of AML associated with tuberous sclerosis

1:13

complex is the epithelioid, a rare type that contains

1:18

few or no fat cells, the epithelioid type of AML.

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Epithelioid AMLs may demonstrate aggressive

1:24

clinical behavior, including extension into

1:27

the inferior vena cava and even metastases.

1:30

So a different behavior for the

1:32

tuberous sclerosis complex type of AML.

1:35

Now in 10 percent of cases where AMLs are really big,

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greater than 4 cm, and that's why I measure the 4 cm

1:41

size, there's an increased risk for potentially life

1:44

threatening hemorrhage known as Wunderlich's syndrome.

1:48

It's also found that tumors that have ruptured

1:51

have sometimes large pseudoaneurysms greater

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than 5 mm in size, suggesting those seen in

1:57

angiography are hemorrhagic pseudoaneurysms.

2:00

Now, rarely, large AMLs can be considerably exophytic

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and difficult to differentiate from perinephric

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liposarcomas, but fortunately, again, that's very rare.

2:12

Features that help suggest an exophytic AML include

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a well-marginated lesion, which our lesion is.

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It's extremely well-marginated.

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A sharp renal parenchymal defect

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with a sharp renal interface.

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We have that here.

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And the presence of enlarged vessels, which you

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may see on a CT angiogram or on a real angiogram.

2:32

Now let's continue looking at our lesion and

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see some of the other characteristics of it.

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Here's a simple T2 without fat suppression.

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And yes, these lesions have a vascular component.

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So, we didn't fat suppress this, so it doesn't

2:47

dissuade me from the diagnosis, the very fact that it

2:50

is somewhat hyperintense on the T2-weighted image.

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Let's look at the diffusion MRI.

2:58

On diffusion MRI, there's no diffusion

3:00

restriction, which you might see with a

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solid, cellular, heavily packed lesion.

3:06

And as you know, there are several causes of diffusion restriction:

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one of which is viscosity, another which is

3:12

cell death, another which is cell packing.

3:15

So this lesion does not demonstrate diffusion

3:18

restriction implicating those underlying etiologies.

3:21

So we're into this diagnosis of

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angiomyolipoma, and we're going to continue

3:26

on discussing it in the next vignette.