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Here we’ll take a look at leukemia.
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It’s a topic that most med students are quite afraid of.
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But not to worry.
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We will go through this together.
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And by the time we’re done, your thoughts will be extremely organized
and you’ll be able to identify your patient very, very confidently.
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Let’s take a look.
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Acute.
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What does acute mean to you?
It means fast.
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What does leukemia mean to you?
It means cancer.
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Okay.
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A cancer developing from where?
Bone marrow.
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That’s where your focus will be initially.
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However at some point in time, you do know that
on your peripheral blood smear you are then going to find an increased number of cells.
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That puts this into leukemia.
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And there is every possibility with the leukemia that
these cells might then enter a lymph node.
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And therefore the presentation here might be very much like a lymphoma
and that will tell you as to when that will be relevant to you
for symptoms and signs as far as the patient is concerned.
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Is it neoplastic leukocytic origin?
If you found predominance of immature cells, which are then called blasts,
Where?
Bone, bone, bone, bone, bone marrow.
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B as in blasts.
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B in bone marrow.
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What is acute?
What does this mean?
Since this is a leukocytic type of neoplasm
that the cell within the bone marrow is not being matured quick enough.
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In fact, many of your cells of the neoplasm remain in its blastic form,
which is a very primitive and very young cell.
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By definition,
ALL or AML which are both acute leukemias,
by definition, you have to find greater than 20% blasts in the bone marrow.
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Once that’s understood, it’s only then we can move on.
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The symptoms in acute leukemia are due to bone marrow failure.
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This results in decreased production of normal blood cells leading to anemia, thrombocytopenia and leukopenia.
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I would like to point out that although the white blood cell count is high, these cells represent the immature, circulating blasts.
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So even though there is an increase in the number of circulating leukocytes,
there is functional leukopenia because these cells do not function properly.
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Usually the first symptom that the patient is exhibiting
would be signs and symptoms of anemia.
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Meaning to say fatigue and tiredness.
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The one that you’re worried about very much in terms of pancytopenia
would be the susceptibility to infections,
leukopenia.
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Definition of acute leukemias referring to both AML or ALL,
greater than 20% blasts in the bone marrow.
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Etiology, chromosomal abnormalities are a possibility
and Down syndrome is something we’ll take a look at.
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We’ll take a look at ALL, ionizing radiation.
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We have chemical exposure or maybe even perhaps alkylating agent.
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Wait, hold down for a second.
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You should be asking yourself what does this mean?
The patient was receiving chemotherapy for another type of cancer.
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And while receiving the chemotherapy unfortunately develops another type of leukemia.
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So even alkylating agents that are being used to prior cancers
might then unfortunately give rise to a new leukemias.
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Age.
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Subtypes:
There will AML/ALL.
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Next, what you want to do with acute leukemias?
So far, you have a definition of leukemias.
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This is a neoplasm of your leukocytic origin from the bone marrow.
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We have greater than 20% blasts from the bone marrow.
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And now, we’ll take a look at the various lineages of your cell or your bone marrow,
the 2 major lineages.
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One lineage will be myeloid.
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The other lineage will be lymphoid.
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If you’re thinking myeloid, it’s all cells
except your T-cells, B-cells and natural killer cells.
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So when you say acute myelogenous leukemia,
you know that you’re dealing with many different types of myeloid cells.
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Hence, you will be using what’s known as FAB classification,
M0 all way out to M7.
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By the time we come to M3 you’ve heard of,
well, this is promyelocyte.
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Hence, M3, which we will be focusing upon,
is called your acute promyelocytic leukemia or promyelocytic leukemia.
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Do not forget the other name.
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By the time you’re still getting to M5, you’re producing more monocytic.
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By the time you’re still getting to M5 to M6 and such,
more RBC’s and M7 will be megakaryocytes.
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All myeloid, all myeloid.
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Disease of immature granulocytes.
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Seen in, well basically, all age ranges.
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Look at this, 15-60,
so the age is not going to tell you much.
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Tell me what you’re going to find in your bone marrow?
Greater than 20% blasts in your bone marrow.
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And if you’re thinking myeloid,
you’re affecting all the myeloid cells except T-cells and B-cells.
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What’s the other type of acute leukemia?
It’s acute lymphoblastic leukemia, would be the better name that you need to know.
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Once again why do we call this lymphoblastic?
Because you will find greater than 20% blasts in the bone marrow.
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Since we’re dealing with ALL, lympho-.
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There’s only 2 types of ALL,
T type and B type,
B type/T type, T type/B type.
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If it’s AML, there is 7 different subtypes
because there are 7 different methods of developing other myeloid cells.
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Clear?
Next.
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Disease of immature lymphocyte, pre-B or pre-T ALLs.
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Typically, now you know that this is the youngest leukemia causing cancer.
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So in this, you’re thinking about age group of, well, less than 15 years of age.
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Number 1 leukemia in this age group.