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What do you think of this MR knee lesion?
Posted by zwfriis_936 on December 24, 2020 at 8:32 pmThis patient referred from outside for biopsy of the abnormality at the distal femur. I think it looks like persistent/reconverted red marrow, but I thought it typically shouldnt cross the physis in this manner. Is it atypical red marrow, or something else? Would you biopsy it, or is there another piece of workup you’d do first?
[attachment=0]leann2001nl replied 3 years, 10 months ago 21 Members · 55 Replies -
55 Replies
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I’ve found in and out of phase helpful before deciding to go to biopsy.
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Unknown Member
Deleted UserDecember 25, 2020 at 4:11 amPlain film?
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Unknown Member
Deleted UserDecember 25, 2020 at 6:43 amb9 something.
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Based on what we have here, it looks like true marrow replacement (no internal fat, very homogenous T1 drop)
There’s no sclerotic margin visualized.
So you are in “marrow replacement lesion NOS” situation.
As Mark Robbin (my MSK mentor) would say: “It you can’t name it, you can’t ignore it.”
Depending on pt age and history I would either biopsy or at the very least close follow. If it just showed up on the Bx schedule I would do it.
(My $0.02 … round blue cells of some sort)
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Unknown Member
Deleted UserDecember 25, 2020 at 7:30 amAgree with dergon.
Btw, does anyone remember that rad who missed lymphoma in distal femur in a young female and got sued and one of the rad heavyweights opined that that a dumb miss or something like that?
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Unknown Member
Deleted UserDecember 25, 2020 at 11:09 am[link=https://www.auntminnie.com/forum/tm.aspx?m=180449&mpage=1]https://www.auntminnie.co….aspx?m=180449&mpage=1[/link]
I can’t find the stupid case where Dr. Bill Bradley majorly dissed a community rad for missing similar lesion.
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Wish we had more discussions like this on AM and less of the typical stuff
by this I mean this thread, not the linked thread with the ivory tower guy crapping on general rads-
Unknown Member
Deleted UserDecember 25, 2020 at 1:39 pmRemoved due to GDPR request
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I was worried about lymphoma too. Interesting that you can still see some trabeculae on the T1 in the lesion.
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Not specific for anything and not typical enough to blow off as red marrow. Definitely can’t just leave it alone.
I think totally reasonable to bx now, but would also agree with a more full workup with plain films/CT, could even do a bone scan to see if there are other lesions elsewhere.
I wouldn’t favor a short term (few months) follow-up but not totally unreasonable. Lymphoma definitely a possibility.
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Thanks for feedback everyone. I agree that it was intersting that you could still see preserved underlying trabecular architecture, but crossing the physis and the T1 signal are worrisome. Also agree that lymphoma a definite possibility. My partner apparantley was shown radiograph of the knee from the orthopod, which was totally normal, lesion couldnt be seen, which also can be the case with lymphoma. No post contrast imaging was done outside. Biopsy is to be done next week I believe, I’ll follow up with results.
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Unknown Member
Deleted UserDecember 25, 2020 at 3:07 pmRemoved due to GDPR request
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Quote from ghostofosler
I was worried about lymphoma too. Interesting that you can still see some trabeculae on the T1 in the lesion.
Yeah … that’s what gave me the round blue cell tumor vibe… they kind of percolate through.
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Dergon,
You think primary lymphoma of bone based on that? Or hard to tell?
Ive seen some lymphomas that were secondary have a look of seeping out of the bone. Many with large soft tissue component.
Thanks.
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Should add…maybe those cases Im thinking of are just larger/grew out of the bone.
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Im not walking out on a limb any further than recommending bx 😉
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The fact that the radiographs was normal makes this even more concerning for lymphoma. Other considerations include plasmacytoma and metastasis. Would absolutely biopsy it.
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It needs a biopsy either way, but would be kinda nice to have pre/post contrast MR, whole body bone scan, and age+Clinical info.
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If it was my case, I’d start with calling patient back for in/out of phase imaging, and contrast.
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Are there any imaging characteristics on IP/OOP and postcontrast that would theoretically lead you to not recommend/perform a biopsy?
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Yea in phase and out of phase isnt going to keep you from biopsying that. Maybe a normal bone scan would, maybe, but youd still follow it at the least.
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The lesion looks neoplastic on T1. Suggest all sequences be obtained ( including post contrast) before biopsy, so that the follow up can be compared to all the pre Bx sequences. The biopsy can and will change the post contrast enhancement pattern. Also, the lesion wasn’t seen on X ray/ so not sclerotic and looks marrow based on MR, so bone scan is of questionable value for other such lesions in the marrow ( which may be smaller and missed).
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Unknown Member
Deleted UserDecember 26, 2020 at 5:38 pmOpposed phase, contrast enhancement, bone scan etc is not going to help to a significant degree; you still won’t really know.
Either you follow it closely, or bx, no other choices.
Of course, lymphoma, when not ever lymphoma?
Would do all the prudent things, of course.
But I’ve never seen a lesion like this that was bad for a lot of reasons, so I bet it’s not; but really I have no idea. Maybe it’s like amyloidosis or some weird manifestation Erdheim-Chester disease. Look forward to the answer. -
If it looks like a classic island of red marrow on out of phase, I don’t think you’d jump to biopsy. (My gut feeling is this is not just red marrow, but that’s how I’d work it up)
Bone scan not very helpful IMO. Negative bone scan could mean myeloma or benign causes. Bone scan only helps if it’s positive and finds additional lesions elsewhere. -
myeloma that size is not going to be radiographically occult, and im betting this knee is not that old. negative bone scan would favor benign which would make you feel better about following it, at least that was my logic, but im no msk.
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Bone scan is unlikely to help but goes into the “you don’t know until you know” category. There is a small chance there is some multifocal pathology going on that isn’t suspected at the time.
I think for the most part, everyone correctly sees the T1 signal/location and thinks path should be involved on this one.
Keep us posted. -
Preserved trabecula and signal characteristics suggests red marrow island…but agree lymphoma remains a consideration.
If additional imaging done get wide FOV of whole femur and contralateral femur to evaluate marrow space for symmetry in case of benign red marrow. If asymmetric then biopsy.
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Contrast and in/out of phase aren’t going to change the differential at all IMO. In fact, where I did fellowship, we completely stopped doing in/out for tumor studies because they never really added anything in our experience. I know that’s a hot take though.
No matter what, a biopsy is indicated.
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I cant wait for the path results. Thanks for sharing this case!
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I rarely find in/out of phase changes what Im going to do or adds anything meaningful. If its a red marrow island or other benign lesion, Im usually pretty confident in this without the in/out phase images.
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Bit more info…patient is late 30s in age, not sure clinical history, knee pain, but not sure if there was an antecedent trauma or anything.
The outside xray was uploaded to our PACS and is indeed totally normal. Patient had a bone scan yesterday, with mild, but definite increased uptake corresponding to the MR lesion, no other abnormal uptake. Biopsy should be in the next couple days I think. -
That looks too distinct and homogenous and poor location for red marrow. Lymphoma and mets are good options. Wouldnt giant cell be good option too? Starts in metaphysis and grows into epiphysis.
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I wouldnt put giant cell very high on the list. Doubtful to be stone cold normal on xray that size and also not great signal characteristics on MR for it.
I doubt its cartilaginous but it is sort of interesting its following native cartilage signal pretty closely on the images provided.
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does that posterior cortex on the sagi bother anyone else or is it just va?
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Unknown Member
Deleted UserJanuary 3, 2021 at 4:45 amWhat would be the approach for biopsying this?
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I would use a posteromedial approach, using the fat plane between the semimembranosus and gracilis tendon. I would not go centrally to avoid the popliteal vessels, and I would avoid lateral to avoid peroneal nerve branches. If it’s not clearly visible with CT, no problem – just use landmarks given size of the lesion.
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What would be the approach for biopsying this?
If there is a chance the lesion may be a primary sarcoma for which surgical resection/ limb salvage will be the treatment, then the biopsy approach should be coordinated with the surgeon. The correct approach will allow the surgeon to excise the tract and not limit options for limb salvage/ flaps etc.
Talk to the surgeon first.
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In general this is true. However, where I did fellowship, we had an understanding that we would take the most direct approach that would avoid crossing multiple muscle compartments and spare neurovasculature. It was very rare for us to coordinate with them directly. That was a stark contrast from where I did residency.
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Path just came back today actually.
B-cell Lymphoma. Bone scan and CT CAP were otherwise negative, so looks like a primary lymphoma of bone. Thanks for all the input and discussion. First case of PBL that I’ve seen in the wild. -
thank you for posting the follow up!
we rarely actually get the confirmation : -
Thanks for follow up!
Good example of a nonspecific case that definitely needs further workup and ultimately biopsy. -
Thanks for posting follow up. One thing everyone should remember is that if a radiograph is normal with an MRI that is frankly abnormal like this, you should strongly consider lymphoma.
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Great case. Thanks for sharing. Hope your patient has a good outcome.
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you can do all the additional imaging, in/out phase, bone scan, followup MRI, xrays, etc.
I think everyone would sleep better at night knowing exactly what that diagnosis is. Whether it is lymphoma, marrow conversion, or something else weird. -
Unknown Member
Deleted UserDecember 30, 2020 at 6:34 am
Quote from dayman
If it looks like a classic island of red marrow on out of phase, I don’t think you’d jump to biopsy. (My gut feeling is this is not just red marrow, but that’s how I’d work it up)
That is very interesting. But how many people here do routine in and out of phase imaging on MSK MRI’s, or how many of you do it on only bone tumor protocols? -
It deserves biopsy. IMO its too dark on the T1 and poor location to be confidently called red marrow. Agree, the preserved trabeculation is reassuring though lymphoma can infiltrate in that way. The location isnt great for PBL (diaphysis/metadiaphysis more common if I recall correctly). I personally wouldnt waste time with in/out phase. I would do post con and probably a CT to make sure I cant see the thing before I schedule biopsy. Feel confident that no one in the world will fault you for biopsy.
MSK rad
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