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Why difference in BMB aspirate vs. core biopsy results?
On my most recent bone marrow biopsy report, which shows details for the aspirate and details for the core biopsy, there is a difference in the total plasma cell percentage reported under each section, and this is confusing me. (The percentage is higher in the core, lower in the aspirate). Is this a usual finding. It's making me think that they didn't get a "good" sample.
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DanaH - Who do you know with myeloma?: Myself, SMM as of 1/2012
- When were you/they diagnosed?: 1/2012
- Age at diagnosis: 54
Re: Why difference in BMB aspirate vs. core biopsy results?
I had two different labs examine one common sample. Both had a "final diagnosis" summary where they called out percentages of lambda plasma cell involvement. I'll be honest and state that I had a hard time really following all of the report leading up to the summary, so I just went with the summary and that's also what my doc used when staging me.
But, with two different labs analyzing the same sample, note that they each came up with different percentages for my plasma cell involvement. This is because even the same technician with the same equipment working on the same sample can come up with different figures depending on the concentration of the plasma cells in a given portion of the same sample. Things are not completely uniformly distributed in the sample and the technician manually counts the plasma cells present in a given area when doing the analysis. The final measurement just depends on what part of the sample pops up when they slip it under the microscope.
This is also why I've learned to treat many of my markers as just rough guides and not to get too worried about small changes from test to test.
I know this doesn't completely answer your question, but thought it might help.
But, with two different labs analyzing the same sample, note that they each came up with different percentages for my plasma cell involvement. This is because even the same technician with the same equipment working on the same sample can come up with different figures depending on the concentration of the plasma cells in a given portion of the same sample. Things are not completely uniformly distributed in the sample and the technician manually counts the plasma cells present in a given area when doing the analysis. The final measurement just depends on what part of the sample pops up when they slip it under the microscope.
This is also why I've learned to treat many of my markers as just rough guides and not to get too worried about small changes from test to test.
I know this doesn't completely answer your question, but thought it might help.
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Multibilly - Name: Multibilly
- Who do you know with myeloma?: Me
- When were you/they diagnosed?: Smoldering, Nov, 2012
Re: Why difference in BMB aspirate vs. core biopsy results?
Remember they are testing two things here. The core sample is the rice-sized piece of your marrow they removed. The Aspirate is the fluid drawn in addition to the core sample. The potential could exist that the two would be different. I can't honestly remember seeing a difference, the doc told me my percentage and I went on from there.
Hope this helps
Hope this helps
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Rugbyhubby
Re: Why difference in BMB aspirate vs. core biopsy results?
Thanks so much Multibilly and Rugbyhubby. Appreciate the explanations very much.
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DanaH - Who do you know with myeloma?: Myself, SMM as of 1/2012
- When were you/they diagnosed?: 1/2012
- Age at diagnosis: 54
Re: Why difference in BMB aspirate vs. core biopsy results?
Dear Dana H,
Great question. You are seeing the burden of myeloma in your bone marrow being estimated by two different techniques.
The first method is to smear the blood sample from the bone marrow (the aspirate) on a slide, count the number of white blood cells you see under the microscope, and determine what percent of the white blood cells are plasma cells.
The second technique is to use a special antibody that specifically "stains" plasma cells and highlights them on a core bone marrow biopsy. This is typically done using an antibody to CD138, which is only expressed on plasma cells in the bone marrow.
When someone is doing a bone marrow aspirate (drawing the blood sample from the marrow space into a syringe), peripheral blood (which contains very few plasma cells) starts to "contaminate" the sample after you have drawn ~3 milliliters of aspirate. The more peripheral blood there is to contaminate the aspirate specimen, the lower the estimated burden of plasma cells. As such, this test can underestimate the actual burden of disease if there is a lot of peripheral blood in the sample. The same problem holds true for flow cytometry as a way of measuring plasma cells in a marrow.
The CD138 stain is done on the core biopsy and is not subject to the dilutional problem. However, myeloma involvement of the marrow space can be quite patchy. As such, you may see variable degrees of staining from one area to the next and determining the overall average is not always so easy.
This is an important issue for a couple of reasons:
Pete V.
Great question. You are seeing the burden of myeloma in your bone marrow being estimated by two different techniques.
The first method is to smear the blood sample from the bone marrow (the aspirate) on a slide, count the number of white blood cells you see under the microscope, and determine what percent of the white blood cells are plasma cells.
The second technique is to use a special antibody that specifically "stains" plasma cells and highlights them on a core bone marrow biopsy. This is typically done using an antibody to CD138, which is only expressed on plasma cells in the bone marrow.
When someone is doing a bone marrow aspirate (drawing the blood sample from the marrow space into a syringe), peripheral blood (which contains very few plasma cells) starts to "contaminate" the sample after you have drawn ~3 milliliters of aspirate. The more peripheral blood there is to contaminate the aspirate specimen, the lower the estimated burden of plasma cells. As such, this test can underestimate the actual burden of disease if there is a lot of peripheral blood in the sample. The same problem holds true for flow cytometry as a way of measuring plasma cells in a marrow.
The CD138 stain is done on the core biopsy and is not subject to the dilutional problem. However, myeloma involvement of the marrow space can be quite patchy. As such, you may see variable degrees of staining from one area to the next and determining the overall average is not always so easy.
This is an important issue for a couple of reasons:
- You need to be sure you are comparing apples to apples when you are looking at the results of your bone marrow biopsy before and after treatment; and
- This can have implications about how someone's disease is labeled. If someone has 6% plasma cells by aspirate and 13% by CD138 on core biopsy, are they an MGUS patient or a smoldering myeloma patient? In my experience, patients with these results tend to behave more like MGUS. As such, I am hesitant to call it smoldering myeloma under those circumstances.
Pete V.
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Dr. Peter Voorhees - Name: Peter Voorhees, M.D.
Beacon Medical Advisor
Re: Why difference in BMB aspirate vs. core biopsy results?
Dear Dr. Voorhees,,
Your response was so extremely helpful ! My quandary actually has been my "label", MGUS or smoldering multiple myeloma. I was told smoldering myeloma due to the plasma core cells and the CD138 staining technique, which was the higher number (6% aspirate, areas of 5%-10% and 5%-15% on the core, which they averaged to 10%, hence, my smoldering myeloma label).
So I thank you for making the time to answer my question .
Best,
Dana
Your response was so extremely helpful ! My quandary actually has been my "label", MGUS or smoldering multiple myeloma. I was told smoldering myeloma due to the plasma core cells and the CD138 staining technique, which was the higher number (6% aspirate, areas of 5%-10% and 5%-15% on the core, which they averaged to 10%, hence, my smoldering myeloma label).
So I thank you for making the time to answer my question .
Best,
Dana
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DanaH - Who do you know with myeloma?: Myself, SMM as of 1/2012
- When were you/they diagnosed?: 1/2012
- Age at diagnosis: 54
6 posts
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