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So this is a classical example of

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a retromolar trigone carcinoma.

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The Retromolar trigone carcinoma is sometimes

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a little bit confusing really based on the

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anatomy, and we just have to remember that the

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retromolar trigone is behind the last molar tooth.

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So let's take a look at that

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all important normal anatomy.

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So what I'm gonna do in this case is I'm gonna

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draw a line down the middle, and I'm gonna

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compare this side with the opposite side.

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Now, when I look at the normal side,

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I'm just gonna show the tumor here.

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We'll talk about this in detail later.

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But when we look at the opposite side, I'm

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gonna point out this muscle right here.

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This is the bator muscle here.

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This area right here is a retromolar Trigone.

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This area right here that I'm contouring,

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this is the ramus of the mandible.

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This is the medial OID muscle,

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and that's the masser muscle.

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That is the all important and a normal anatomy

0:51

in the region of the retromolar trigone.

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So now let's talk about the tumor

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that's involving the retromolar trigone.

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So here is a tumor that's

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involving the retromolar trigone.

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Notice it's behind the maxillary

1:03

tuberosity, which is here.

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It's anterior to the ramus of the mandible.

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It's anterior to the oid muscle, and

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it's anterior to the masser muscle.

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So this is the classical appearance of a

1:14

retromolar trigone, so the surgeons can see

1:17

the retromolar trigone, but it's probably the

1:19

cancer that's most commonly underdiagnosed.

1:22

Why?

1:22

Because it's lateral and it's behind the tooth.

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So it's very, very hard for the

1:26

surgeons to look behind the tooth.

1:29

Also, because this tumor is in close proximity

1:32

to the ramus of the mandible, these tumors

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have a tendency to have early bone erosion.

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So some of the spread patterns that we need

1:40

to include in our report are the following.

1:42

Number one, here's our bator

1:45

muscle that's located here.

1:46

Is the tumor growing along the bator muscle?

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So let's take a look at this

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tumor here on the right hand side.

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Notice it is growing along the buck ator muscle.

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There's no way for the surgeon to see that

1:57

when they're performing direct endoscopy,

1:59

which means they're looking in the mouth.

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Secondly, because this tumor is in close proximity

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to the ramus of the mandible, is the bone eroded?

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Because if the bone eroded, it's

2:09

gonna upstage the lesion to a T four.

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So when we look at this, notice how the anterior

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portion of the ramus of the mandible is eroded.

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On this non-contrast T one weighted images,

2:20

notice how this gray now is involving the

2:23

anterior aspect of the ramus of the mandible.

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Note, the normal high signal in the

2:28

marrow on the non-contrast T one.

2:30

So all of a sudden what we've said.

2:33

Is that, gosh, this is a retromolar trigon carcinoma.

2:36

It's extending laterally to the buccal area.

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It's eroding bone.

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So all of a sudden now it's a T four lesion,

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and when we give contrast on the fat suppressed

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images, we can see abnormal enhancement.

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Involving the marrow of the brains of the

2:51

mandible would suggest that this is either direct

2:54

tumor invasion or peritumoral inflammation,

2:58

and compare that with the opposite side.

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So in summary, this is a retromolar trigon carcinoma.

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We talked about the abnormal anatomy, we talked about

3:06

the spread patterns, and a few things that you should

3:09

include in your report that's gonna make a difference

3:12

in how these patients are treated and staging.