Haematology Myeloproliferative Disorders Flashcards

1
Q

Myeloproliferative disorders: Description

A

Clonal haematological disorders characterised by over-production of blood cells and a tendency to transformation to acute leukaemia.

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2
Q

Myeloproliferative disorders: Epi

A

Generally diseases of middle or older age groups.

Incidence: 2 cases per 100,000

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3
Q

Myeloproliferative disorders: Three related disorders with similar acquired genetic defects (e.g. Janus Kinase Jak-2 mutations)

A
  1. Primary polycythaemia
  2. Essential thrombocythaemia (increased platelets)
  3. Idiopathic myelofibrosis
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4
Q

Myeloproliferative disorders: Mixed myeloid progenitor

A

RBC/Platelets/ Neutophil/Monocyte/ Basophil/Eosinophil

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5
Q

Myeloproliferative disorders: Similar disorders

A

Chronic myeloid leukaemia (CML)

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6
Q

Myeloproliferative disorders: Essential thrombocythaemia

A

Increased platelet number

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7
Q

Myeloproliferative disorders: Myelofibrosis

A

Affects stomal calsin BM – scarring and fibrosis in bone marrow

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8
Q

Polycythaemia → Defined by

A

Defined by the packed cell volume (PCV): a raised PCV of >0.51 in males and >0.48 in females requires further investigation.

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9
Q

Polycythaemia → Measure

A

The True red cell mass and the plasma volume can be measured.
Involves radionucelotide labelling of red cells and albumen, respectively (less common).

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10
Q

Polycythaemia → The absolute measurements allows

A

“True” polycythaemia to be distinguished from an “apparent” polycythaemia (decreased plasma volume).

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11
Q

Polycythaemia → Symptos and Signs of Primary Polycythaemia

A

Hyperviscosity:
Hypervolaemia:
Hypermetabolism:

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12
Q

Hyperviscosity:

A

Haemostasis (thrombosis – stroke, transient ischaemic attacks, digital ischaemia), haemorrhage, headache

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13
Q

Hypervolaemia:

A

Plethora, hypertension and splenomegaly

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14
Q

Hypermetabolism:

A

Pruritis, weight loss, sweats, gout

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15
Q

Polycythaemia → Packed cell volume >0.51 (males)

>0.48 (females) with a raised red cell mass (absolute) definition

A

Primary polycythaemia

Secondary polycythaemia

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16
Q

Polycythaemia →Packed cell volume >0.51 (males)

>0.48 (females) Normal red cell mass diagnosis

A

Apparent polycythaemia

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17
Q

Polycythaemia → True polycythaemia

A

Raised RBC

Plasma volume slightly reduced but overall volume higher

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18
Q

Polycythaemia → Apparent polycythaemia

A

Overall blood volume is less. Red cell mass normal (Can occur burns, alcohol, smoking)

19
Q

Differential diagnosis of a true polycythaemia

A

Primary Polycythaemia

Secondary Polycythaemia

20
Q

Secondary Polycythaemia

A

Drive from EPO due to a stimulus.
• Hypoxaemia e.g. chronic lung disease, cyanotic congenital heart disease, sleep apnoea.
• Renal disease e.g. hypernephroma, polycystic kidney disease (cysts causes pressure on cells leading to increased EPO)
• Miscellaneous e.g. hepatomas, cerebellar haemangioma, massive fibroids, high oxygen affinity haemoglobins.

21
Q

Symptoms and Signs of Primary Polycythaemia

A
  • Facial plethora
  • Headache
  • Mental clouding
  • Pruritis
  • Hypertension
  • Splenomegaly
  • Gout
  • Occlusive vascular lesions e.g. stroke, transient ischaemic attacks, digital ischemia
  • Bleeding
  • Hyper viscosity
22
Q

Polycythaemia Specialist Investigations

A
  1. Serum Erythropoietin → Low in primary polycythaemia
  2. Jak 2 mutation
  3. Bone marrow examination
  4. Abdominnal ultrasound to assess spleen size
23
Q

Jak 2 mutation

A

Specific V617F mutation in Jak 2 signal transduction protein linked to erythropoietin receptor. This “activating” mutation promotes proliferation of stem cells.
Identified in 90% of patients with polycythaemia vera and 50% of patients with essential thrombocythaemia and myelofibrosis (30-50%) – permanently switched on – increased RBC.

24
Q

V617F

A

Found on cell surface involved in transfer of EPO binding signal to the cell

25
Q

Bone marrow examination for

A

Erythroid hyperplasia

Fibrosis (low levels)

26
Q

Treatment

A
  1. Repeated venesections to maintain a PCV of <0.45 (aiming for (slightly lower than normal)
  2. Hydroxyurea if there is also thrombocytosis (concern increase risk of leukaemia.
  3. Low doe aspirin (if there are no bleeding manifestations) – prevent arterial clots (can’t tolerate other treatments)
  4. Radioactive phosphorus
27
Q

Radioactive phosphorus

A

Single disease controls disorder for 12-18 months but associated with increased risk of leukaemia.
Reserved for elderly frail patients.

28
Q

Progression and Prognosis

A

Untreated patients: survival 18 months (clots and myelofibrosis and leukaemia)
Treated patents: survival 10-15 years
In the longer term, 20% of patients transforms to myelofibrosis and about 5% to acute leukaemia (need monitoring)

29
Q

Essential Thrombocythaemia: Definition

A

A myeloproliferative disorder characterised by the presence of a persistent thrombocytosis (platelet count >450 x 109/L) increased + 600

30
Q

Essential Thrombocythaemia: JAk2 mutation

A

Positive in 50% of cases: useful for diagnosis (not as useful as in polycythaemia)

31
Q

Essential Thrombocythaemia: Diagnosis

A

Otherwise, this is a diagnosis of exclusion and other reactive causes of a raised platelet count first need to be considered: e.g. infection, inflammation, malignancy and bleeding (reactive picture).

32
Q

Essential Thrombocythaemia: Presentation

A
  • 25-50% of patients present with microvascular occlusive events (e.g. burning pain in extremities or digital ischaemia), major vascular occlusive events or haemorrhage (interference with clotting cascade).
  • Erythromelalgia in essential – redness and burning the feet and hands
  • Livedo reticularis in essential thrombocythaemia.
33
Q

Essential Thrombocythaemia: Blood film in thrombocythaemia

A
  • Large Platelets (variation in size)
  • Iron deficiency
  • Hypochrominc RBCs – Iron deficiency
  • CHECK THIS
34
Q

Essential Thrombocythaemia: Bone marrow morphology in essential thrombocytaemia

A
  • Megakaryocytes and abnormal nucleation

* CHECK THIS

35
Q

Essential Thrombocythaemia: Treatment

A
  1. Low dose aspirin (unless history of bleeding)
  2. Hydroxyurea (carbomide(same thing))
  3. Anagrelide (younger patients) – chemoagents
    Transformatino to myelofibrosis or acute leukaemia may occur in a small minority of patients long term – Primary polycythaemia.
36
Q

Idiopathic Myelofibrosis: Main Clinical Features

A
  • Bone marrow fibrosis (scar tissue leading to extramedullary)
  • Extramedullary haemopoiesis (blood cell production in the liver and spleen)
  • Splenomegaly – often massive
  • Anaemia with leucoerythroblastic blood picture (precursors to RBC/WBC which you wouldn’t expect to see
  • Weight loss, fatigue, bleeding
37
Q

Idiopathic Myelofibrosis: The Primary Malginant Process involves

A

Megakaryocytes: generate growth factors such as platelet-derived growth factor which stimulate fibroblast proliferation (stromal cell)

38
Q

Idiopathic Myelofibrosis:Fibroblast proliferation produce

A

Produce reticulin and scar bone marrow
1st – proliferation phase
2ndry – Splenomegaly and drop blood counts

39
Q

Idiopathic Myelofibrosis: X-ay changes

A

Myelosclerosis

40
Q

Idiopathic Myelofibrosis:Blood Picture

A

Leucoerythroblastic blood picture

41
Q

Idiopathic Myelofibrosis:Bone Marrow histology

A

Normally – fat cells and organised set of cells.
‘Starry night’
Stranding of cells into other areas – fat spaces

42
Q

Idiopathic Myelofibrosis: Determine severity of bone marrow histology

A

Fibrosis criteria to determine severity

43
Q

Idiopathic Myelofibrosis: Treatment

A

Blood Transfusions if symptomatic anaemia. Thrombocytopnaenia – symptomatic difficulty w/ splenomegaly therefore increased destruction and therefore not helpful.
Splenectomy to correct anaemia or treat painful enlargement of the spleen.

44
Q

Idiopathic Myelofibrosis:

Prognosis

A

2-4 years with death due to haemorrhage, infection or transformation to acute leukaemia → poor

Stem cell transplantation for younger patients (<65 years).
Jak 2 inhibitors for recently licensed: early trials show reduction in splenomegaly and constituitional symptoms and improved survival.