Should plasmacytomas be biopsied and tested genetically?

A plasmacytoma is a type of tumor made up of abnormal plasma cells that can develop in soft tissue or bones.

Can a plasmacytoma have a different genetic makeup than the rest of your myeloma?

In this video, we'll explore whether myeloma specialists recommend biopsying and genetically testing these tumors to uncover potential differences.

Should plasmcytoma be biopsied and tested genetically?

This is a clinical question. I guess that would make the argument that wherever the plasma cell is proliferating and if it's proliferating at different locations, so you've got a bone marrow where there's plasma cells. But now if you have a solid tumor, like a plasmacytoma I would still argue that you want to test that particular site, because there's no assurance that the plasmacytoma has all of the same genetic mutations and variations as the tumor that's in the bone marrow.

The word plasmacytoma has many connotations, so the more imaging we do, the more we realize that myeloma is a lumpy, bumpy disease. A lot of patients have solid foci of disease in the bone bone marrow. We call them focal lesions.

A plasmacytoma tends to imply a lesion at a specific site that's grown to form a tumor. And often there's a differential diagnosis problem. So is it myeloma? Is it a plasmacytoma? Is it a sarcoma or is it another type of metastasis to bone.

So you need to have the biopsy to see the plasma cells characterize them to know what you're dealing with. Because turns out plasmacytomas are quite sensitive to radiation. And so they need to be internally fixed, irradiated stabilized. And then you can get on and treat the rest of the disease throughout your body.

Some people have isolated plasmacytoma. And if they're small and you do an MRD test somewhere else in the body and there's no cells there, maybe you could just get away with treating it locally.

The question that comes up is whether one should biopsy a plasmacytoma in a person who has a history of multiple myeloma. And there's two aspects to this. And there's two aspects to this. There's the academic aspect.

We know that there could be genetic differences in that plasmacytoma that may not be present in the remainder of the cells in the bone marrow. But one challenge to that is that even if you do that, what if you biopsy in a site that doesn't have that change, where you to biopsy ten times, or what are you better off maybe getting more and more samples or even sampling more plasmacytomas?

So I think practically it's not that important unless something happens that the patient is not responding to the treatment. So in my practice, I don't do rapid biopsies of plasmacytomas often unless something is happening that makes us worry that we're not seeing the expected behavior.

And that could be either growth of the plasmacytoma because somehow it's been refractory to the drugs in use. And that is possible because sometimes plasmacytomas maybe, areas with slightly more advanced myeloma cells, more clonally advanced.

We can sometimes see and I've seen a few times in my practice too, that the plasmacytomas. It can start depositing proteins, amyloid like proteins, and they may grow them even have symptoms and pain because of this.

So that may be another reason why something may not go in the direction that we think it should be going.

We can sometimes use plasmacytomas also to gauge response to treatment. So we have a person who has multiple plasmacytomas. And we start therapy. It's something visual that we can see that the medications are working.

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