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Dr. P here with a patient who's 44 years old,

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3 00:00:04,760 --> 00:00:08,340 who complains of a mass in the, in the plantar area.

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And this patient has an abnormality

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between M3 and M4, and it's got a little

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vanilla and a little chocolate in it.

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Now, if you've gone through this

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series, you know that we've shown

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some intermetatarsal space masses.

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And this one has characteristics

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of two different types of masses.

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It's got that peanut-shaped gray signal,

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which is characteristic of a Morton's neuroma

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or perineural fibroma, or fibrous reaction.

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We like those to be about six to eight millimeters

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in size before we use the term Morton's neuroma;

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otherwise, we call them PNFs, perineural fibrosis.

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But when we scroll through this, the dorsal

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aspect of it has a very high signal intensity.

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Now, that is difficult to appreciate

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in the long axis, sort of coronal-like

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or axial-like projection, depending

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upon how you view this projection.

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There's the fibrous component of it, there's

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the high signal component of it, and adjacent

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to it is some fluid in the joint capsule of M4.

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So you can see that's very fluid-like.

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So, in this case, we have to quote a former

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commercial, a breath mint and a candy mint.

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We have both the fibrous components of

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a Morton's neuroma and the fluid-like

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components of a bursal collection.

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And then as we scroll around, we don't want to

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get too much tunnel vision, so let's just scroll

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around and see what everything else looks like.

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There's a little bit of fibrous

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reaction between M2 and M3, but

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nothing coalescent, nothing mass-like.

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So this we would call PNF. And then some of

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you might latch on to this, right there,

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as a dorsal prolapsing Morton's neuroma.

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And this is a potential pitfall

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in diagnosis, which is just volume

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averaging of muscular tissue, remember.

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M1, M2 Morton's neuromas are quite uncommon

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because of the digital nerve anatomy.

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So we're sort of done, but we keep

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scrolling and all of a sudden we find

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this weird looking thing that has some

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high signal and some low signal inside it.

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It looks like an archery target and

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there it is on the T1-weighted image.

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There it is on the water-weighted

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image, the T2-weighted image.

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Let's blow it up a little bit

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to get a better view of it.

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That was somewhat unexpected.

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Let's see what it looks like on the

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standard T2 coronal, and there it is.

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And so there's a very broad

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differential diagnosis here.

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It looks like the cyclops eye, right?

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There's the pupil, and there is the

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rest of the eye, perhaps the sclera.

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And while there is a differential diagnosis

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here that I'm not going to go into at length,

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this was an incidentally discovered lesion.

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It's a low-grade form of

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malignancy, believe it or not.

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It's dermatofibrosarcoma protuberans, which likes the

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chest, the trunk, and perhaps the head and neck.

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It can have a fibrous component to it.

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They tend to be a little bit more

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homogeneous, higher signal intensity.

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But some of them have coalescent

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fibrous signal intensity inside.

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They can be a little bit exophytic.

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They tend to occur a little more frequently in

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men than women, and this happened to be a man.

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So, this is a twofer.

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We've got a, actually a threefer.

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We've got a Morton's neuroma, a

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bursal cyst, and, incidentally

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discovered, dermatofibrosarcoma protuberans.

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Dr. P, out.