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<v ->That brings us to the next topic.

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And it's a bit of a complicated topic

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because of the terminology changes undergoing

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for vascular lesions of joints and elsewhere.

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We call this typically a synovial hemangioma.

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It's one of many vascular tumors and vascular malformations.

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And this particular lesion can arise in a joint,

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most commonly the knee joint.

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It can arise in an isolated fashion in a joint.

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It can be combined with involvement of the bone

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or of the soft tissues or various combinations of those.

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And in some of the patients you'll get an underlying history

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that there are other problems

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with fancy names of other syndromes

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that are associated with vascular tumors

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and vascular malformations,

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more commonly monoarticular

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and very characteristic MR imaging findings.

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I'll show you a few cases.

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I include this slide just to show you some

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of the more recent classifications of vascular tumors.

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And you can see that they're listed

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as synovial hemangiomas, venous hemangiomas,

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arteriovenous hemangiomas and malformation.

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Some people will classify them

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as low-flow or high-flow lesions

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which will influence the way they appear

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on the MR examination.

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Here's one example of a synovial hemangioma.

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There is involvement of other tissues here,

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but most of the hemangioma is located within the joint

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and within the adjacent bone.

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It has a channel-like appearance.

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In this particular case

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we don't see low signal to suggest high-flow

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or a phlebolith,

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which would also produce areas of low signal.

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So this was a synovial hemangioma.

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Here's another one.

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This more looks like lake-like collections,

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which is characteristic in some of the synovial hemangiomas.

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This one located in the area of the suprapatellar recess.

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There probably is a little

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of an extra-articular component as well.

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And another one, this one arising both,

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it looks like in the joint and in the prefemoral fat.

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There is some vascularity in the subjacent bone

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shown here by one of the arrows.

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So you can in fact see involvement

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of bone and joint and soft tissue.

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Another one here located mainly

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in the intracapsular fat off this fat pad,

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tubular shadows, serpentine-like appearance,

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very characteristic.

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Now with synovial hemangiomas

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that have led to extensive bleeding,

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which they certainly can within a joint,

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you will get hemosiderin deposition,

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shown in this particular case here,

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taken from the literature.

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But I give you a long list of possible diagnoses

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related to chronic hemarthrosis.

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So you see, there are many things that you have to think of,

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including hemophilia and other bleeding disorders.

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So although when you see hemosiderin,

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you at least should consider you're dealing

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with a synovial hemangioma,

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but consider a long list of differential possibilities.

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And as I mentioned, I think, I originally became familiar

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with these entities back decades ago,

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then the days of conventional radiography

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when we came across three or four cases like these

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from an article,

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these are taken from the article we wrote,

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where the arthropathy of the knee looked like hemophilia.

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It had this etched appearance

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with irregularity of the femoral condyles,

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the widening of the intercondylar notch,

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everything that you think about with hemophilia,

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even on this case, it looks a bit like hemophilia,

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but the addition was the presence of phleboliths.

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And because of that, we were able to diagnose preoperatively

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that these were hemangiomas,

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but they do produce a hemophilia-like arthropathy

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especially in the knee.