What is bone marrow involvement?
bone marrow is a soft tissue that is inside some of
the larger bones. It contains stem cells which develop
into the three different types of blood cell: red blood cells white blood cells,
We can think of the bone marrow as a nursery for all blood cells.
Since normal cells are present in the marrow, it's not unusual or
unexpected that lymphoma cells will also present in this organ. The involvement
in the marrow is determined and
measured by a biopsy - a sample of the cells in the region.
Lymphoma cells can accumulate in the marrow to a degree that they
crowd out normal cells and inhibit the "birth" of normal blood cells
from stem cells. This may lead to a decrease in red blood cells
(anemia, leading to fatigue) or platelets (thrombocytopenia, risk of
bleeding), or other white blood cells (neutropenia, increased risk
of infection) etc., which would be detected by blood tests.
The list of complications sounds ominous, but watching your
counts is one important way that our doctors monitor the condition
and make decisions about when to treat. We don't always get into
trouble from lowering counts .. the lymphoma does not always
accumulate in the marrow to a degree that causes such problems. It
may be at say 20% involvement and stay that way for many years. Some
of us may have little or no bone marrow involvement. Each case can
Importantly, lymphoma in the marrow can be treated effectively,
just as well as lymphoma cells that accumulate in lymph nodes. The
blood counts will improve with effective treatment.
Is bone marrow involvement common in lymphoma?
It's common to be diagnosed with lymphoma at an
advanced stage (III or IV) and with bone marrow involvement.
While this might seem alarming, you should know that advanced stages
of lymphoma can be treated successfully, and that lymphoma in the
bone marrow is as reversible with treatment as lymphoma anywhere in the body.
One way to understand this is to compare lymphoma
with a so-called solid tumor, such as a prostate cancer. Here
the cell of origin of the cancer does not normally exist anywhere
but in the prostate. So when you find malignant prostate cells
in the bone marrow, you have a serious problem. For blood cells,
however, we expect these cells to be anywhere in the lymphatic or
circulatory system, including the bone marrow.
Bone marrow involvement and survival for low grade NHL?
"Conclusion. The presence of bone marrow infiltration at
diagnosis did not significantly affect the prognosis of low grade non-Hodgkin's Lymphoma."
A diagnosis of lymphoma in the bone marrow can only be established by obtaining a bone marrow specimen for
analysis - a bone marrow biopsy.
This test might be done for staging purposes in order to provide a
baseline of where the lymphoma is so that it can be monitored for
progression, guide treatment, and judge response to subsequent
A negative bone marrow result means that there's an improved chance that the marrow is clean or relatively clean, but it's not a conclusive result.
Similarly, if we scooped a bucket of water out of a swimming pool at night
we might find no leaves in the bucket - but we could not conclude the pool is without leaves - only that the
scoop we took did not find any.
Imaging such as MRI or PET can "help increase the positive
yield of bone marrow biopsies by guiding the marrow sampling
procedures to sites of relatively hypercellular marrow." (Magnetic
Resonance Imaging of the Bone Marrow in Hematologic Malignancies
Bilateral testing (taking sample
from both sides) will be more reliable: (Bone marrow biopsy for the staging of non-Hodgkin's
lymphoma: bilateral or unilateral trephine biopsy?
Tumori. 1995 Nov-Dec;81(6):410-3.
NOTE: Lymphoma cells are very
very small. For example, a one centimeter tumor has about 1
billion lymphoma cells. A few number of lymphoma cells will not be
detected by many standard tests. Only a significant
number of cells sufficient to form a mass (a tumor) will be
detected by imaging and other tests.
One very sensitive test for lymphoma cells is called PCR. It
can detect for the presence of genetic translocations (that are
unique to some kinds of lymphoma in the sample).
Returning to the analogy of testing
for leaves in a pool, a sample taken with a bucket that has no
leaves (tumors) might have small traces of leaf fragments
(individual tumor cells) that are not visible with plain sight,
which might be detected by other, more sensitive, tests.
Gene Rearrangement, Quantitative Real-Time PCR
"The t(14;18) translocation is characteristic of B-cell
lymphomas, occurring in up to 90% of follicular lymphomas.
It is also found in 20% to 30% of diffuse large B-cell lymphomas
Also see: What is PCR Testing?