Hey this is Dr K from imedicalschool and today
we are going to talk about multiple myeloma. Let’s first start off by talking about the
different forms of immunity. Your body can fight off infections via two main types of
immunity. The types of immunity are cellular immunity and humoral immunity. Cellular immunity,
as it sounds, utilizes cells to fight off infections such as cytotoxic or killer T cells.
The second form of immunity is humoral immunity. Humoral immunity works through the utilization
of antibodies. Now cells are needed to produce the antibodies. These cells that produce antibodies
are called plasma cells. Plasma cells are important in the pathophysiology of multiple
myeloma. Multiple myeloma is the expansion of a single
clone or type of plasma cell. Due to the proliferation of a single clone of plasma cells there is
a sharp rise in the production of a single type of antibody resulting in what is called
a monoclonal gammopathy. The rapid expansion of a clone of plasma cells and antibody production
can lead to bone pain, lytic lesions, anemia, hypercalcemia, and acute kidney injury.
Generally multiple myeloma is quite rare and only makes up about 1% of all cancers. There
has been a noted increased incidence of multiple myeloma among African Americans while there
is a decreased incidence of myeloma among Asians and Mexicans. The median age of onset
for multiple myeloma is 66 and the cases of familial inheritance are extremely rare.
Now the symptoms and signs of myeloma are quite generalized and numerous. Symptoms and
signs include anemia, fatigue, weight loss, acute kidney injury, hypercalcemia, and bone
pain. In terms of the anemia it is usually a normochromic normocytic anemia. The anemia
results due expansion of plasma cells in the bone marrow impairing RBC production, as well
as, progressive kidney injury leading to poor erythropoietin production. Erythropoietin
or EPO is a hormone made famous by Lance Armstrong and is a hormone that stimulates the bone
marrow to increase RBC production. One of the hallmarks of multiple myeloma is
extreme bone pain. A common finding is a reduction height that results due to vertebral fractures.
Generally bone pain worsens with movement and tends to be seen in up to sixty percent
of multiple myeloma patients. Proteinuria is another common finding in multiple
myeloma . It is important to point out that urinalyses only detect albumin in the urine.
In multiple myeloma patients are spilling immunoglobulins into the urine and thus their
urine dipsticks will show no protein though in reality they are spilling a significant
amount into their urine. If sulfosalicyclic acid is added to the urine sample the immunoglobulins
present can be visualized. In addition to using sulfosalicyclic acid you can obtain
a 24 hour urine and send it for protein electrophoresis and immunofixation to determine the amount
and type of protein present in the urine. The electrophoresis should show a single large
peak indicating one type of immuglobulin replicating out of proportion to other immunoglobulins.
The significant proteinuria that develops in myeloma leads to acute kidney injury. There
are two types of acute kidney injury encountered in multiple myeloma. Myeloma can cause light
chain cast nephropathy, otherwise known as myeloma kidney, and light chain amyloidosis.
In myeloma kidney the immunoglobulins result in large waxy casts in the urine with a negative
dipstick urine. In light chain amyloidosis the immunoglobulins deposit into the kidney
causing significant glomerular damage and loss of albumin into the urine resulting in
a positive dipstick. In rare circumstances patient can develop
cord compression. Spinal cord compression is an oncological emergency. In myeloma it
can be due to an extramedullary plasmacytoma. A plasmacytoma is a mass of proliferating
plasma cells that can occur within or outside the bone marrow. If it occurs in the spine
it can compress the spinal cord causing severe damage. The first step is to obtain STAT imaging
of the spinal cord to determine if compression is present. Patients with cord compression
diagnosed clinically or via imaging should be started on dexamethasone. Neurosurgery
should be consulted for further evaluation and decompression. Other features you may see in multiple myeloma
include the rouleax formation. In a peripheral blood smear you may see red blood cells stacked
on top of one another like a stack of coins. This occurs due to the hyperviscocity linking
of RBCs by immunoglobulins. You can see the coin stacks that are created as pictured here.
In a bone marrow biopsy you will notice a large proliferation of plasma cells. Finally
patients will usually undergo a skeletal survey if they are diagnosed with myeloma. These
films may show osteolytic lesions of the skull and vertebra. In addition they may show diffuse
osteopenia and even vertebral fractures. Now that we discussed signs and symptoms let’s
talk about the initial workup. If you suspect someone has multiple myeloma it is important
to order the proper initial workup. First start off with a CBC with a differential to
identify if an anemia is present. In addition look at a peripheral blood smear to identify
if rouleax formations are present. Next obtain an SPEP and UPEP to identify production of
a monoclonal production of antibodies. Other labs include LDH and CRP to identify inflammation
and cell turnover. In addition obtain a chemistry to identify any electrolyte abnormalities
or kidney dysfunction. Lastly obtain a beta 2 microglobulin as an elevation is this test
is a poor prognostic sign. If the workup is consistent with myeloma obtain a bone marrow
sample and a bone survey. The diagnostic criteria for myeloma stress
whether organ damage is taking place. A patient needs three criteria met before diagnosing
multiple myeloma. These include M protein in serum and/or urine. In addition the bone
marrow must consist of at least 10% of plasma cells, and finally there must be some evidence
of organ impairment. The organ damage that is described can be represented by the acronym
CRAB and includes calcium levels, renal insufficiency, anemia, and bone lytic lesions.
Differential diagnoses include MGUS or monoclonal gammopathy of undetermined significance and
smoldering multiple myeloma. MGUS a serum monoclonal gammopathy but has
plasma cells at less than 10 % of the bone marrow with no end organ impairment as represent
by CRAB or lytic lesions. In smoldering multiple myeloma serum monoclonal gammopathy is elevated
with>10% of plasma cells in the bone marrow but there is no organ impairment. Treatment of multiple myeloma includes stem
cell transplant and chemotherapy. Chemotherapeutic agents include bortezomib and thalidomide.
Well that is a brief review of multiple myeloma. If you liked this video share this with your
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you next time.