What are the different types of plasmacytomas? How are plasmacytomas treated?

What is a plasmacytoma? What are the different types of plasmacytomas?

So what? Let's start with. So let's talk a little bit about plasmacytomas. Because it's kind of you know, this is where multiple myeloma is different from like other blood cancers. It's like leukemia. It's almost more like lymphoma where people can get, you know, lumps or tumors or like a solid tumor. So it's different.

And what a plasmacytoma is basically it's a tumor of myeloma cells. And, these can form anywhere. They can form in the bone, in which case we call it an osseous plasmacytoma, they can form, adjacent to the bone. We call that paramedullary disease. So by the bone, we're kind of coming out of the bone. And then we have extra medullary disease, which is where it's just outside the bone could be in the liver, it could be in sinuses, could be on the skin. People can develop plasmacytoma cells.

And so, you know, how are these discovered? Well, they can really happen at any sort of time point along a patient's time with multiple myeloma. Sometimes they can just pop up unexpectedly. Sometimes we see them happen when the monoclonal proteins are monitored, and suddenly they have, you know, new pain. And we do a scan and there's a plasmacytoma.

So, you know, they happen kind of throughout. They might happen at the time of diagnosis. We often see them in the spine causing these compression fractures. Sometimes they can cause cord compression where they press on the spinal cord. And that's considered an oncologic emergency that we sometimes treat with. We often treat with radiation, steroids, maybe surgery to try to make sure, folks don't suffer from neurologic injury. Because if we don't treat that in time, people can become paralyzed. So that's an emergency.

But plasmacytomas can occur anywhere. Plasmacytoma, what is the plasmacytoma? That's an aggregation of plasma cells in one area. So it's like a big ball of plasma cells, and it can be either within the bone, but often outside the bone. So you'll see them in an aggregation. That's what we call extramedullary. So an extramedullary plasmacytoma is an aggregation of plasma cells not in the bone. And you can still see a plasmacytoma that's in the bone that, say, for example, grows out.

So it's sometimes not that bad if you only have one of these things and nothing else. If you were to develop a single plasmacytoma inside the bone it's called a solitary plasmacytoma. And those often can be treated very conservatively and managed locally, often with radiation and then close follow up. There are some features that would suggest perhaps this might progress, perhaps some molecular testing or, finding minute amounts of abnormal plasma cells in the marrow.

So long story short, early on, plasmacytoma can be very limited. Multiple plasmacytomas can be a bad prognostic sign, especially in the context of recurrence, where there are multiple plasmacytomas that pop up outside of the bone. They're often difficult to control if they're in organs that normally don't have plasma cells, such as the liver or the skin, or other organs where you just don't usually see this.

What does a solitary plasmacytoma? Solitary plasmacytoma is when we find in somebody a plasmacytoma usually it's found on like a scan. Someone typically has symptoms. Often these are in the spine. That's been the most common in my kind of, experience. Sometimes they're in the... They can be extramedullary.

So there's two when we're talking about plasmacytomas. There's osseous plasmacytoma whenever that's in the bone there's extramedullary plasmacytoma that is outside the bone those are much less common. Most plasmacytomas are osseous. Most of them are in the spine, sometimes in other sites.

How we know it's really a solitary plasmacytoma because the thing when we find the plasmacytoma what we want to do is evaluate the extent of the disease. So, you know, where there's smoke, there's fire, right? When we find a plasmacytoma we have to make sure someone doesn't have multiple myeloma. That's the key thing because the treatments are very different.

So we would usually get a thorough assessment for multiple myeloma, including the bone marrow biopsy, blood and urine testing for a gammopathy, and total body imaging with like a PET CT or a diffusion-weighted MRI. And we want to make sure there's no other sites. And the only way we know if someone really has a solitary plasmacytoma, is if they just have one site of disease, one plasmacytoma, nothing else on the imaging.

And, a bone marrow biopsy that shows less than 10% plasma cells. So if it's greater than 10%, that's multiple myeloma. And we treat that like multiple myeloma, solitary plasmacytoma that we treat with radiation typically higher doses than we might treat with palliative radiation where we are trying to treat pain. Sometimes that's in the range of the radiation. Oncologists give is 40 to 50 gray. That's the unit of measurement that they give.

Whereas for a plasmacytoma might be 20 gray. So it's a higher dose. And we're really trying to eradicate all the disease in that area.

There's two kinds of types of plasmacytomas or solitary plasmacytomas. And there's plasmacytomas with some bone marrow involvement. Some folks have called that plasmacytoma plus or maybe plasmacytoma with minimal marrow involvement. Really they're treated the same way. We're going to give radiation.

But the difference with the solitary plasmacytoma compared to the plasmacytoma plus, is that there's a higher risk of progression to myeloma with the plasmacytoma plus, as one might expect, when we already see evidence in the bone marrow, but they're treated right now, they're treated the same way.

And so we typically would give the radiation and then monitor, you know, everyone has their own kind of, recipe for how can they monitor patients. But I typically see people every three months and get serial imaging studies for a while, especially for the first couple of years when they're going to be at the highest risk of progression to multiple myeloma.

Is total body irradiation used if there are multiple plasmacytomas? We, you know, the limited scenarios where we use total body radiation. Really conditioning for allogeneic transplant. So TBI or total body radiation is used sometimes for certain types of transplants. Specifically the allogeneic transplants where people get cells from other people, from a donor.

We sometimes use TBI, but for as a treatment for plasmacytoma that's not something we would do. It's really the TBI is specifically part of a conditioning for some types of transplants, but not for treatment.

So we use involved field radiation. So this is where the radiation oncologist, you know, finds a field and shoots the radiation, the photons or sometimes the protons at the tumor to kill the cancer cells. And sometimes we might have to target different spots depending on what's most active.