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Haematology > Myeloproliferative disorders > Flashcards

Myeloproliferative disorders Flashcards

1
Q

Myeloproliferative disorders : Definition

A

Myeloproliferative disorders involve the uncontrolled proliferation of a single type of stem cell.

  • Cause irreversible replacement of the bone marrow with fibrous tissue (fibrosis)
  • Considered a form of cancer occurring in the bone marrow, although they tend to develop and progress slowly.

They have the potential to transform into acute myeloid leukaemia.

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2
Q

Myeloproliferative disorders : Types

A
  • Primary myelofibrosis
  • Polycythaemia vera
  • Essential thrombocythaemia
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3
Q

Myeloproliferative disorders : Genetics

A
  • JAK2 gene mutation : Mostly associated with Polycythemia Vera
  • MPL
  • CALR

contribute to abnormal signaling pathways and increased proliferation of hematopoietic cells.

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4
Q

Primary Myelofibrosis : Definition

A

Clonal proliferation of hematopoietic stem cells,
Single mutated stem cell gives rise to a population of abnormal cells

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5
Q

Primary Myelofibrosis : Pathophysiology

A

1 . Gene mutation
Abnormal cell signally - increases proliferation of stem cells

2 . Abnormal hematopoietic stem cells proliferation in bone marrow
* Leukocytosis
* Thrombocytosis

3 . Excessive GF and Cytokines released - triggers fibrosis

4 . Bone marrow fibrosis
* Fibrobroblasts replace bone marrow with collagen scar tissue

5 . Bone marrow dysfunction
* Lack of erythrocytes produced - Anaemia

6 . Extramedullary Hematopoiesis
* Due to bone marrow fibrosis - haemtopoesis progresses in Spleen and Liver
* Splenomegaly, Hepatomegaly

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6
Q

Primary Myelofibrosis : Blood findings

A
  1. Anaemia - impaired erythropoesis particularly extramedullar
  2. Leukocytosis - raised WCC due to initial proliferation
  3. Thrombocytosis -raised platelets due to intial proliferation

When extramedullary haematopesis progresses - will cause drop in WCC and platelets also.

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7
Q

Primary Myelofibrosis : Management

A
  1. No active treatment for mild disease with minimal symptoms
  2. Supportive management of complications, such as anaemia, splenomegaly and portal hypertension
  3. Chemotherapy (e.g., hydroxycarbamide) to help control the disease
  4. Targeted therapies, such as JAK2 inhibitors (ruxolitinib)
  5. Allogeneic stem cell transplantation (risky but potentially curative)
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8
Q

Essential Thrombocytopenia : Definition

A

Chronic myeloproliferative neoplasm characterized by abnormal proliferation of ;
* Megakaryocytes in the bone marrow, which produce platelets

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9
Q

Essential Thrombocytopenia :Pathophysiology

A

1 . JAK 2 mutation - promote abnormal proliferation of megakaryoblasts
2 . Bone Marrow Hyperplasia
Increased production of abnormal platelets
3 . Platelet overproduction
4 . Splenomegaly
* High number of platelet sequester in the spleen

  1. Thrombotic complications
    * Increased coagulability due to + platelets in the blood leads to - high risk of PE, DVT, arterial thrombosis
  2. Haemorrhagic complications
    * Abnormal plateltes - dysfunctional in controlling bleeding
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10
Q

Essential Thrombocytopenia : Complications

A
  1. Thrombotic complications
    * Increased coagulability due to + platelets in the blood leads to - high risk of PE, DVT, arterial thrombosis
  2. Haemorrhagic complications
    * Abnormal platelets - dysfunctional in controlling bleeding
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11
Q

Essential Thrombocytopenia : Blood findings

A
  1. Raised platelet count
  2. Megakaryoblasts
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12
Q

Essential Thrombocytopenia : Management

A

Management of essential thrombocythaemia may involve:

  1. Aspirin to reduce the risk of thrombus formation
  2. Chemotherapy (typically hydroxycarbamide) to help control the disease
  3. Anagrelide is a specialist platelet-lowering agent
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13
Q

Polycythemia vera : Definition

A

Polycythemia vera (PV) is a chronic myeloproliferative neoplasm characterized by the excessive production of red blood cells, white blood cells, and platelets in the bone marrow.

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14
Q

Polycythemia vera : Pathophysiology

A
  1. JAK 2 mutation
    * Mainly affects the erythropoietin receptor, leading to increased sensitivity of hematopoietic cells to erythropoietin
    * Also effects - lymphoblasts and megakaryocytes to some degree
  2. Erythrocytosis - main compoenent
    * Overproduction of RBCs
    * Hyperviscosity of blood
  3. Bone Marrow Hyperplasia:
    * Hyperplasia of the erythroid, myeloid, and megakaryocytic lineages

4, Leukocytosis and Thrombocytosis present
* Increased megakaryocytes

  1. Splenomegaly
    * High RBCs, increased sequesteration in the spleen
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15
Q

Polycythemia vera : Complications

A

Increased risk of thrombosis - due to high viscosity of blood
Leading to : myocardial infarction, stroke or venous thromboembolism

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16
Q

Polycythemia vera : Clinical presentation

A

Clinical signs of polycythaemia include:

  • Ruddy complexion (red face)
  • Conjunctival plethora (the opposite of conjunctival pallor)
  • Splenomegaly
  • Hypertension
  1. Pruritus - worst after taking hot showers
  2. Tingling, burning and numbness in arms, hands and feet
17
Q

Polycythemia vera : Blood findings

A
  • Elevated Hematocrit and Hemoglobin:
18
Q

Polycythemia vera : Management

A
  1. Venesection - keep the haemoglobin in the normal range
  2. Aspirin - reduce the risk of thrombus formation
  3. Chemotherapy (typically hydroxycarbamide) to help control the disease
19
Q

Myelofibrosis : Definition

A

Myelofibrosis can result from primary myelofibrosis, polycythaemia vera or essential thrombocythaemia.

Myelofibrosis is where the proliferation of a single cell line leads to bone marrow fibrosis,

20
Q

Myelofibrosis : Pathophysiology

A
  1. Proliferation of a single cell line (Any of the myeloproliferative disorders)
  2. Triggers - Fibroblast growth factor and cytokine release
  3. Bone marrow replaced with fibrotic tissue
  4. Fibrosis leads to dysfunctional production of Blood cells;
    low haemoglobin (anaemia),
    low white blood cells (leukopenia)
    low platelets (thrombocytopenia).
  5. Extramedullar haematopesis - due to bone marrow non function

Production of blood cells in the;
* liver and spleen causes hepatomegaly, splenomegaly, and portal hypertension.
* Around the spine, it can cause spinal cord compression.

21
Q

Myelofibrosis : Clinical presentation

A

Systemic symptoms

  • Fatigue
  • Weight loss
  • Night sweats
  • Fever

There may be signs and symptoms of underlying complications:

  • Anaemia (tiredness, shortness of breath and dizziness)
  • Splenomegaly (abdominal pain)
  • Portal hypertension (ascites, varices and abdominal pain)
  • Low platelets (bleeding and petechiae)
  • Raised haemoglobin (itching, headaches and a red face)
  • Low white blood cells (infections)
  • Gout is a complication of polycythaemia
22
Q

Myelofibrosis : Diagnosis

A

Gold standard : Bone marrow biopsy

Aspiration may be “dry” with myelofibrosis, as the bone marrow has turned to scar tissue

Blood film

  • Teardrop-shaped red blood cells
  • Anisocytosis (varying sizes of red blood cells)
  • Blasts (immature red and white cells)
23
Q

Myelofibrosis : Main complication

A

It has the potential to transform into Acute Myeloid Leukaemia.

24
Q

Myelodisplastic syndrome : Definition

A

Myelodysplastic syndrome is a form of cancer caused by
* mutation in the myeloid cells in the bone marrow,
* resulting in ineffective haematopoiesis

25
Q

Myelodisplastic syndrome : Pathophysiology

A

1 . Mutations
* contribute to the dysregulation of hematopoiesis.

2 . Myeloid stem cells - abnormal development and maturation of myeloid precursor cells

3 . Ineffective Hematopoiesis:
* Abnormal myeloid precursor cells produced in the bone marrow are often nonfunctional and ineffective.
* This results in inadequate production of mature, fully functional blood cells.

4 . Peripheral Blood Cytopenias
* > 1 blood lineage of Myeloid precursor cells affected

26
Q

Myelodisplastic syndrome : Clinical presentation

A

They may present with symptoms of:

  1. Anaemia (fatigue, pallor or shortness of breath)
  2. Neutropenia (frequent or severe infections)
  3. Thrombocytopenia (bleeding and purpura)
27
Q

Myelodisplastic syndrome : Diagnosis

A
  1. Full blood count will be abnormal. There may be blasts on the blood film.
  2. Bone marrow biopsy is required to confirm the diagnosis.
28
Q

Myelodisplastic syndrome : Management

A

Management

  1. Watchful waiting
  2. Supportive treatment (e.g., blood or platelet transfusions)
  3. Erythropoietin (stimulates red blood cell production)
  4. Granulocyte colony-stimulating factor (stimulates neutrophil production)
  5. Chemotherapy and targeted therapies (e.g., lenalidomide)
29
Q

Myelodisplastic syndrome : Complication

A

Increased risk of : Acute Myeloid Leukaemia devlopment

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