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3. Haematology > Haemopoiesis & Disorders > Flashcards

Haemopoiesis & Disorders Flashcards

1
Q

Where does haemopoiesis occur in adults?

A

Red bone marrow, found in:

Axial skeleton (vertebrae, sternum, sacrum, pelvis)
Skull
Ends of femurs

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2
Q

Where does haemopoiesis occur in adults?

Consider haemopoiesis in infants, too.

A

Foetus:
0-2 months: yolk sac
2-7 months: liver, spleen
5-9 months: bone marrow

Children:
Bone marrow (all bones)
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3
Q

List the stages in erythroblast maturation, and give a brief description of important cells.

A

Proerythroblast

Basophil erythroblast

  • Little haemoglobin
  • Begins condensation of nucleus etc.

Reticulocyte

  • Contains RNA/nucleus remnants
  • Enter blood

Erythrocyte

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4
Q

How does EPO affect haemopoiesis?

Describe its mechanism of action.

A

Stimulates production of proerythroblasts from myeloid precursors; increases speed of RBC maturation.
Mechanism:

  1. Hypoxia in kidneys stimulates productino of hypoxia-inducible factor 1 (HIF-1)
  2. HIF-1 acts as a transcription factor for the EPO gene
  3. HIF-1 binds to the hypoxia response element
  4. This causes increased RNA transcription, and therefore increased EPO production
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5
Q

What do 4 cell categories myeloid stem cells turn into?

There are 6 end products.

A

Reticulocytes
-Erythrocytes

Megakaryocytes
-Platelets

Monoblasts
-Monocytes (–>macrophages)

Myeloblasts

  • Neutrophils
  • Eosinophils
  • Basophils (–>mast cells)
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6
Q

What 3 cell categories do lymphoid stem cells turn into?

There are 3 end products.

A

Pre B cell
-B lymphocyte (–>plasma cell)

Pre T cell
-T lymphocyte

NK precursor
-NK cell

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7
Q

List 4 characteristics of haemopoietic stem cells.

A
  1. Capacity for self-renewal
  2. Unspecialised
  3. Quiescent (phase G0 of cell cycle)
  4. Only undergo cell division occasionally; can only divide about 20x in lifetime
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8
Q

Where are haemopoietic stem cells found?

A
  1. Bone marrow
  2. Peripheral blood (after release is stimulated by granulocyte colony stimulating factor, G-CSF)
  3. Umbilical cord blood
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9
Q

What types of division can haemopoietic stem cells undergo?

A

Symmetrical (either increases/decreases stem cell numbers)

Asymmetrical (maintains stem cell numbers)

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10
Q

Describe the 2 main features of the haemopoietic cell’s environment that affect its division.

A

Niche - collection of signalling and internal cell cues in the microenvironment

Stroma - bone marrow microenvironment containing ECM and stromal cells

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11
Q

Which signalling pathways are involved in the haemopoietic stem cell niche?

A

Wnt

SHH (sonic hedgehog)

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12
Q

Which stromal cells are involved in supporting haemopoietic stem cells? (5)

What is their function? (2)

A 
Macrophages
Fibroblasts
Endothelial cells
Fat cells
Reticulum cells

Function:

  1. Adhesion molecules - provide structural support for stem cell
  2. Growth factors - stimulate stem cell
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13
Q

Describe the features of leukaemogenesis. (3)

A

Dysregulation of cell growth and differentiation
Mutations in stem cells
Clonal proliferation of leukaemic cells with no differentiation

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14
Q

Briefly describe the patholophysiology of leukaemia. (4)

A
  1. Injury to haemopoietic stem cells causes a mutation
  2. This forms abnormal leukaemic myeloid/lymphoid cells
  3. These abnormal cells divide to form clonal leukaemia cells
    a. These are formed so quickly that they can’t mature properly - many blasts present
  4. This creates an abnormal blood cell population
    a. This prevents the formation of normal blood cells, leading to anaemia, thrombocytopenia etc.
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15
Q

What are the 2 types of pre-leukaemic conditions?

A 
Myeloproliferative disorders (MPDs)
Myelodysplastic syndromes (MDSs)
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16
Q

List 3 examples of myeloproliferative disorders (MPDs).

A

Polycytemia rubra vera
Essential thrombocytosis
Myelofibrosis

17
Q

Define myeloproliferative disorders (MPDs).

A

Clonal disorders of haemopoiesis resulting in increased numbers of one or more mature blood cells

18
Q

Define essential thrombocytosis.

What is it caused by? (2)

A

Platelets: 600+ x10^9/L

JAK2 mutation
Calreticulin mutation

19
Q

Describe the clinical features of essential thrombocytosis. (3)

A

High RBC/WBC/platelet levels
Thrombotic events (e.g. MI, stroke)
Splenomegaly

20
Q

How is essential thrombocytosis classified? (3)

A

Low risk:

  • Age <40 yo
  • No high risk features

Intermediate risk:

  • Age 40-60 yo
  • No high risk features

High risk:

  • Age 60+ yo
  • High risk features, including:
    1. Platelets 1500+
    2. Previous thrombosis
    3. Thrombotic risk factors
21
Q

How would you treat essential thrombosis? Consider the different risk groups.

A

LOW RISK:
Aspirin OR anti-platelet drug

INTERMEDIATE RISK:
Aspirin PLUS hydroxycarbamide

HIGH RISK:
Aspirin PLUS hydroxycarbamide PLUS other treatments

22
Q

Apart from the standard therapies, list 4 other treatments which can be used for essential thrombocytosis.

A

Anagrelide (inhibits megakaryocyte differentiation)
IFN alpha
Busulphan
Ruxolitinib (JAK2 inhibitor)

23
Q

Define myelodysplastic syndromes (MDS).

A

Dysplasia and ineffective haemopoiesis in at least 1 type of myeloid series, caused by progressive bone marrow failure

24
Q

List 4 examples of myelodysplastic syndromes (MDS).

A

Refractory cytopenia
Refractory anaemia with ring sideroblasts
Refractory anaemia with excess blasts
Fanconi anaemia

25
Q

What can cause myelodysplastic syndromes (MDS)? (2)

A

Previous chemo/radiotherapy

Acquired cytogenic abnormalities

26
Q

Describe the clinical features of MDS. (5)

A 
Progression to AML
Asymptomatic
Infections
Bleeding 
Fatigue (due to anaemia)
27
Q

What is the IPSS score used for?

What features does it take into account?

A

Measuring risk of MDS progressing to AML

Features:

  • Bone marrow blasts (%)
  • Karyotype
  • Cytopenias present
28
Q

How would you manage myelodysplastic syndromes (MDS)? (5)

A 
Blood/platelet transfusions
Growth factors (EPO, G-CSF)
Immunosuppression
Chemotherapy
Allogenic stem cell transplant
29
Q

Which genes are involved in Fanconi anaemia?

A

BRCA 1/2

3. Haematology (13 decks)

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