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This is a skeletally immature patient with a benign bone tumor.

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Whenever I see a tumor sort of starting out or involving the epiphysis,

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and it has relatively well defined margins, the patient is skeletally immature,

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even if you describe this tumor to me and told me exactly where

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the location was in the epiphysis, skeletally immature, before I even see

0:28

the images, I'm already thinking chondroblastoma, because it happens so

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frequently in this location that you have to consider that as a primary

0:38

diagnosis. So I have three images here for you to look at.

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We've got a coronal T1-weighted image. We have a coronal fat-suppressed

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fluid-sensitive sequence, and we have a coronal T1 fat-saturated post contrast

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image. Don't let this serpiginous, almost ugly looking enhancement pattern,

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heterogeneous nodular, fool you into thinking that this is something malignant.

1:03

If you have a rounded, fluid sensitive, bright,

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what almost looks like cartilage in the T1 weighted sequence, lesion involving

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the epiphysis, even if it goes through the growth plate and involves the

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metaphysis, chondroblastoma should be at the top of your differential diagnosis.

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Can other things cause this? Yes, of course. Enchondromas can do this.

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If the growth plate was fused, maybe I would think of a giant

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cell tumor. Eosinophilic granuloma, infection. All of those are possible,

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but the most important finding, the most important thing you should be thinking

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about is chondroblastoma. I'll give you a few clues. One is this sort

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of lobular margin, and second, and which I think is one of the

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most important things to look at, is edema. No self respecting chondroblastoma

1:53

will present without edema. 95% of cases of chondroblastoma should have

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bony involvement. If you have something that looks like chondroblastoma

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but there's no bony involvement, think about other differential diagnoses.

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This is a wonderful example of chondroblastoma. Why?

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Centered in the epiphysis, it's eccentric in its location in the epiphysis,

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it approaches the articular surface but doesn't disrupt it,

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and it can go into the metaphysis, and it does cause a lot

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of edema. Enhancement, sure, you do have some enhancement, and it can be

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very ugly looking as you see over here. Is there a joint effusion?

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No, but you may have joint effusion, so its presence or absence isn't

2:35

really helpful for you. Oftentimes it may elicit a periosteal reaction,

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but it may not. The key important finding, again, is edema in the

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adjacent bone marrow and location. Location, location, location. If you

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see something in the epiphysis, it's going to be chondroblastoma until proven

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otherwise. I'm going to show you next, another case of chondroblastoma that's

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involving the knee, so pay attention to that vignette also.