Gas and fluid in the costalcartilage?

[Xue Heng]

Hi, Steve! Thank you again for providing this forum to discuss various US cases.
Recently there is a case that really confused me.
He was a 44 year-old male with rheumatoid arthritis.
After admitted, he had sudden severe chest pain, which was around second left costalcartilage.
When I scanned the location of tenderness, I found flowing gas and fluid inside the costalcartilage.
The patient also had confluent B lines on the lung surface nearby, which may not related to the chest pain.
The patient then had chest CT, but no corresponding positivie finding was observed.
The chest pain resolved quickly, and the patient did not have repeated US exam.
Thank you, Steve.

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[Stephen Bird]

Well Xue,

I have never seen this before !

But I guess we don’t actually scan the costal cartilage with much detail very often.

It is really common to see calcifications in the costal cartilage as a normal variation, however this is not what you have found.

I agree it is some sort of fluid moving within the costal cartilage,

I don’t agree there is any gas within the fluid.

I think the echogenic material is more consistent with some debris within the fluid rather than gas as gas has a fairly characteristic appearance on ultrasound which I think is absent here.

As you scan through on the video clip I feel like there is some calcification in the costal cartilage and a thin area of unossified costal cartilage where you are observing this appearance.

Could you see it in the shore axis of the rib to show the movement was within the costal cartilage and not between them?

I have considered an artefact, however I don’t think I can explain it as an artefact and the movement of the debris within the fluid is consistent and looks real.

My hypothesis would be that the cartilaginous component of the costal cartilage has some fluid tracks within it as a developmental feature and that there is debris formed within that fluid which moves as a result of pressure and postural movement of the costal cartilage when the patient breathes.

This is purely a hypothesis!!!

I would love to ask a thoracic surgeon of the costal cartilage can naturally contain pockets of gelatinous material or fluid within the structure of the costal cartilage. If the answer is yes, this is what you are observing.

If the answer is no, and costal cartilage are ALWAYS solid blocks of dense cartilage then I have no idea!

I can’t explain it as a pathological condition and I don’t think it represents any lung pathology so I am not surprised the CT was normal.

What about an MRI of the chest Xue, not on this patient but in general. Do you ever see areas of high signal indicating liquid pockets in the cartilaginous costal cartilage?

This is a great observation by you Xue and I will be fascinated to get to the bottom of it.

If anyone else has seen this or has any alternative hypothesis please add to the post.

Great case Xue,

Let us know your ongoing thoughts,

Steve.

[Xue Heng]

Thank you again, for your long answer.
I agree with you that there is no air but only debris within the fluid.
Because the findings were so astonishing, I forgot to scan the short axis of the costal cartilage.
I also agree that costal cartilage are solid blocks of dense cartilage, there should be no fluid in it.
If there is new information about this patient, I would post it here.
Thank you, Steve!

[Stephen Bird]

Hi Xue,

As always you provide the most amazing cases and high quality images for us to enjoy and consider,

I am perplexed by this appearance and will consult my brains trust to see if there is any consensus.

I suspect this will remain a mystery for a while,

It is a very mysterious appearance,

If you have any other imaging or clinical follow up that would be most welcome,

Please examine some MRI volumes to see if costal cartilage is always solid cartilage or if there is occasional liquid islands within the cartilage.

I think you have the mystery case of the year so far Xue,

I always love your work and attention to detail,

Please keep it coming and share your amazing cases through this forum,

Happy scanning,

Steve

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