ICL 10.1 & 10.2: Leukemia Flashcards
which cell types are in the myeloid cell line?
platelets
RBCs
granulocytes: neutrophils, basophils, eosinophils
monocyte
macrophages
which cell types are in the lymphoid cell line?
NK cells
B cells –> plasma cells
T cells
What differentiates leukemia from lymphoma?
leukemia arises from lymphoid or myeloid cells, starts in the bone marrow, and then spreads to the blood stream
lymphoma arises from lymphocytes, and starts in lymph nodes then spreads to blood stream
but both are malignant diseases of hematopoietic cells
what are the two major groups of leukemias?
- acute leukemia vs. chronic leukemia
2. myeloid vs. lymphoid leukemias
what are the main characteristics of acute leukemias?
- appear suddenly
- have a devastating clinical course if untreated
- composed of very immature hematopoietic cells
what are the main characteristics of chronic leukemias?
- much more indolent
- may persist for years even without treatment
- composed of cells at a more mature stage of development
what is the marker for lymphoid vs. myeloid leukemia?
Tdt is a marker for lymphoid leukemia
MPO is a marker for myeloid leukemias
what does ALL stand for?
Acute Lymphoblastic Leukemia
what is ALL?
a malignant entity in which very early lymphocyte precursors called lymphoblasts proliferate in the bone marrow and blood
these malignant lymphoblasts divide very quickly, filling up the bone marrow and crowding out normal hematopoietic precursor cells, leading to serious consequences for the patient if not treated immediately
so eventually the amount of mature functioning cells decreases a lot - so you have less RBCs, platelets, everything!
what are the three main types of lymphocytes?
- B cells (adaptive immune system)
- T cells (adaptive immune system)
- NK cells
(innate immune system)
what are B cells?
make antibodies
in charge of the humoral arm of the adaptive immune response
what are T cells?
they use cytokines and other cell surface molecules to mediate the cellular arm of the adaptive immune response
what cells are malignant in ALL?
acute lymphoblastic leukemia comes from either malignant B cell or T cell precursors
NK cells and their precursors have their own malignancies that are separate from ALL
what’s the clinical presentation of ALL?
- neutropenia = bacterial infections, fever
- anemia = fatigue, no energy
- thrombocytopenia = bleeding, petechiae, epistaxis, gum bleeding
- hepatosplenomegaly
- lymphadenopathy
- testicle enlargement (esp. ALL)
- bone pain
- possibly asymptomatic
what population is ALL more common in?
MUCH more common in children
also associated with Down’s Syndrome
T cell vs. B cell ALL
B cell ALL – typically bone marrow involvement first
T cell ALL – Lymph node involvement first
what does the bone marrow of an ALL patient look like?
diffuse, massive proliferation of lymphoblasts
the lymphoblasts are medium-sized cells with a super high nuclear/cytoplasmic ratio and fine chromatin
basically there’s just a ton of big plain purple cells with like no cytoplasm (go look at slide 24)
nucleoli can also be seen which is typically not visible in more mature cells
what does the CBC of an ALL patient look like?
severely increased WBC count because you’re making all these immature lymphoblasts (like 70,000/mmˆ3!!!)
normal blood cells like RBCs, normal WBCs, and platelets are usually decreased in number
what is flow cytometry allow us to do?
it enables us to determine immunophenotype
this test is looking for specific cell surface antigens
these surface markers sometimes change as the cell matures
flow cytometry helps us determine what kind of leukemia and lymphoma it is!
also it’s not invasive…
what are the surface proteins found on T cells?
CD3 and CD5
flow cytometry will show you which surface markers on which molecules to help you identify them!
which are the surface proteins found on helper T cells?
CD4
flow cytometry will show you which surface markers on which molecules to help you identify them!
which are the surface proteins found on cytotoxic T cells?
CD8
flow cytometry will show you which surface markers on which molecules to help you identify them!
which are the surface proteins found on B cells?
Ig, CD10, CD23, CD19, CD20, CD21
flow cytometry will show you which surface markers on which molecules to help you identify them!
which cell marker is specific to lymphoblasts and therefore important in ALL diagnosis?
TdT
all lymphoblasts express TdT!! (terminal deoxynucleotidal transferase)
this is supposed to disappear as cell matures
so if there’s a lot of TdT it tells you that there’s lots of immature cells
then you can do flow cytometry to determine if it’s B cell ALL (CD10, 19, 21, 23) or T cell ALL (CD2, 3, 4, 8)
what is the overall prognosis for ALL?
children have a good prognosis!
most children achieve a complete and durable remission that lasts at least 5 years
however, adults have a lower survival rate
if pt. has CD10 B-ALL, better overall prognosis
what are some good prognostic features of ALL?
- WBC count at presentation (<10,000 = good prognosis)
- Hyperploidy (presence = good prognosis)
- Immunophenotype: B-ALL better prognosis vs. T-ALL
what does it mean if a blood sample is Tdt+?
it means there’s lots of immature lymphoblasts!
what does AML stand for?
acute myeloid leukemia
what population is AML most common in?
most common in adults over age 45!!!!
what is AML?
a cancer of the blood arising from myeloid precursor cells
this includes platelets, RBCs, granulocytes and monocytes aka everything except lymphocytes….
the bone marrow is making abnormal myeloblasts (a type of white blood cell), red blood cells, or platelets
progresses quickly if left untreated
what must be present in a bone marrow biopsy or blood smear for AML to be diagnosed?
≥ 20% blast cells or “blast equivalents” must be present in the bone marrow for a diagnosis of AML
what is a blast equivalent?
in some types of AML, the malignant cell is a somewhat more mature than a blast
ex. in acute promyelocytic leukemia, for example, there are numerous malignant promyelocytes but not very many myeloblasts…
in these types of AML, we use the term “blast equivalent” instead of blasts for whatever immature call that is proliferating the most
what’s the clinical presentation of AML?
decreased amounts of normal cells
increased risk of infection due to neutropenia and too few neutrophils
increased risk of bruising and bleeding due to thrombocytopenia
anemia due to too few RBCs
pretty similar clinical presentation to ALL
what does the blood smear of an ALL patient show?
> = 20% blasts or blast equivalents
presence of Auer rods!! (cytoplasmic inclusions that are formed from the abnormal fusion of azurophilic, or primary, granules)
Auer rods are present in a certain subset of AML so just remember that the absence of Auer rods doesn’t exclude AML!!
so if a blast has Auer rods, you can be sure it’s a myeloblast. If it doesn’t have them, though, it could still be a myeloblast (or it might be a lymphoblast)
what are Auer rods?
cytoplasmic inclusions that are formed from the abnormal fusion of azurophilic, or primary, granules
diagnostic of AML
slide 33
how are the different types of AML categorized by the FAB system?
based on the FAB system
AML subtypes were made because myeloid progenitor cells can form form RBCs, platelets, basophils, neutrophils, eosinophils, and monocytes
M0-M7 subtypes
focuses on morphology and cell line
what are the 8 AML subtypes according to the FAB system?
M0-M3 involve neutrophil precursors;
M4-M5 involve monocytic precursors.
M6 involves immature RBCs
M7 involves immature cells from the platelet lineage
what is the M0 subtype of AML?
acute myeloblastic leukemia with minimal differentiation
involves neutrophil precursors
what is the M1 subtype of AML?
acute myeloblastic leukemia without maturation
involves neutrophil precursors
what is the M2 subtype of AML?
acute myeloblastic leukemia with maturation
involves neutrophil precursors
what is the M3 subtype of AML?
acute promyelocytic leukemia (APL)
involves neutrophil precursors
this is the AML that has Auer rods!!!
what is the M4 subtype of AML?
acute myelomonocytic leukemia
involves monocytic precurors
what is the M5 subtype of AML?
acute monocytes leukemia
involves monocytic precursors
what is the M6 subtype of AML?
acute erythroid leukemia
involves immature RBC
what is the M7 subtype of AML?
acute megakaryoblastic leukemia
involves immature cells from platelets linage
which AML is the one with Auer rods?
acute promyelocytic leukemia (APL)
involves neutrophil precursors
this is the AML that has Auer rods!!!