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Dr. P here. 11-year-old, with a mass that

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3 00:00:05,130 --> 00:00:09,080 is movable, not very firm, and the

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child does not report the mass growing.

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It's a good companion case to any sort of cystic

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type mass, but once again, in companionship with

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some other cases, when you diagnose a cyst on MRI,

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you've got to have high signal that's homogeneous

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on the water-weighted image, which we have.

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But on the T1-weighted image,

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which we have here, the signal intensity

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should be lower than that of muscle.

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If we go to some muscle, muscle's kind

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of gray, and then we go to our mass,

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which is a bit exophytic and weird.

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Here it is here.

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It's about the same as muscle or higher than

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muscle, which puts it in a whole other category.

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It could be a proteinaceous cyst,

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could be a myxoid tumor, could be an

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epidermoid, could be a cystic schwannoma.

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It could even be a varix.

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You know, you'd think it would have bloody

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signals of varix, but frequently you don't

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have methemoglobin staining much in a varix.

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So all those things would factor

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into the differential diagnosis here.

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Now we've got a long axis coronal appearing image

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in which the exophytosis of the lesion, kind of

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a lobulated appearance, is apparent here in the

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axial, it's a little more sessile looking,

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but in no way do we see it communicate with the joint.

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In fact, if we look at its tail, it goes

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right to the middle of the phalanx, not to

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an articular space, which is very helpful.

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It also does not really

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intertwine with the tendon.

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The tendon's over here on the sagittal

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image, and our lesion is exophytic.

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So yes, it is adjacent to it.

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So I wouldn't fault you for

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giving ganglion pseudocysts

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as a differential diagnosis here, although

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in cases like this, what I might do is

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I might do ultrasound with color flow Doppler

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to see if it has any arterial or venous flow.

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I would also, because of the unusual nature

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of it, I would inject it to see if it

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enhances, which would take you away from

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ganglion pseudocysts, and related disorders,

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away from capsular cysts, away from pure

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cysts, which we already know it's not,

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and towards something that enhances like a myxoid

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tumor or other lesions that are more solid like.

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So, what is the differential diagnosis here?

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I think we've given you

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most of the considerations.

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It's certainly not a tenosynovial cyst.

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Cystic schwannoma does remain

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in the differential diagnosis.

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A varix does remain in the differential diagnosis

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because the neurovascular bundle is planted

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eccentrically, plantar, here and here.

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And so this is off to the side.

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You know, when it's perfectly midline,

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I go away from neurovascular tumors.

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So neurovascular tumors is probably where

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I'm gonna put my stake in the ground.

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And this came out and it

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was a little bit surprising.

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It was a lymphangioma.

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Now, lymphangiomas are strange birds.

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They are usually apparent when the patient

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is born, about anywhere from 65% to 90%

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of the time, depending on who you read.

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We've got really small ones that occur in

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the subcutaneous area like this one,

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and these are usually the capillary variety.

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The cavernous variety likes the mouth, the tongue,

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the salivary glands, and the septa in muscle.

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The cystic ones, which are most familiar to those

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of you that are in training and to the head and

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neck radiologists like the head and neck region,

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the mediastinum, the pleura, and the axilla.

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When you look at these, some of them will have

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sort of a solid internal character to them because

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you've got debris or blood, especially inside.

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And when you get the orbital

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hemangiomas, you know, they bleed more

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frequently than the hemangiomas do.

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So the final diagnosis in our 11-year old

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is lymphangioma capillary type.

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Let's move on, shall we?

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Dr. P out.