Myeloproliferative Disorders

Question 1

What are myeloproliferative disorders?

Answer 1

Clonal expansion of myeloid stem cells
–> granulocytes, RBCs + platelets
Maturation relatively preserved

Question 2

What are the different types of myeloproliferative disorders?

Answer 2

Polycythaemia vera (raised RBCs)
Essential thrombocytosis (raised platelets)
Myelofibrosis (increased fibroblast activity)
CML (raised WBCs/granulocytes)

Question 3

What would be seen on a FBC in polycythaemia vera?

Answer 3

Raised Hb/Hct with erythrocytosis

Question 4

Which mutation is commonly seen in polycythaemia vera?

Answer 4

JAK2

Question 5

What are the clinical features of polycythaemia vera?

Answer 5

May be asymptomatic
Thrombosis or haemorrhage
Headache, dizziness
Itch (may be triggered by hot water)
Plethora (facial redness)
Erythromelalgia (burning fingers/toes)
Splenomegaly
Gout

Question 6

How is polycythaemia vera diagnosed?

Answer 6

FBC –> Hct > 0.52 men, > 0.48 women
Blood film –> increased RBCs
JAK2 mutation testing

Question 7

How is polycythaemia vera treated?

Answer 7

Venesection until Hct < 0.45

- aspirin

Question 8

What are some causes of secondary polycythaemia?

Answer 8

Chronic hypoxia:
- smoking, sleep apnoea, lung disease, high altitude
Raised erythropoetin:
- renal cell carcinoma, polycystic kidney disease, hepatocellular carcinoma

Question 9

What are some causes of pseudopolycythaemia?

Answer 9

Reduced plasma volume but normal RBCs

–> dehydration, diuretics, obesity

Question 10

What is essential thrombocytosis?

Answer 10

Uncontrolled production of abnormal platelets (can be > 1000)

Question 11

What are the clinical features of essential thrombocytosis?

Answer 11

Bleeding, commonly GI
Arterial + venous thrombosis
Headache, dizziness, chest pain
Erythromelalgia
Livedo reticularis
Splenomegaly

Question 12

How is essential thrombocytosis diagnosed?

Answer 12

Exclude reactive thrombocytosis + CML
Genetic testing for JAK2, CALR, MPL mutations
–> 10-20% will be triple negative

Question 13

How is essential thrombocytosis treated?

Answer 13

Aspirin

Question 14

What are the features of myelofibrosis?

Answer 14

Marrow failure
Bone marrow fibrosis
Extramedullary haematopoesis –> massive hepatosplenomegaly

Question 15

How is myelofibrosis diagnosed?

Answer 15

Blood film:
- leukoerythroblastosis (myelocytes + myelobloasts)
- teardrop RBCs (poikilocytes)
Bone marrow aspirate failure --> DRY TAP
Bone marrow biopsy --> fibrosis