Myeloproliferative disorders

Question 1

What are myeloproliferative disorders?

• Ph+ve
• Ph-ve (3)

Answer 1

Group of disorders characterized by clonal proliferation of one/ or more haematopoetic component i.e. increased production of mature cells

• Ph +ve = CML
• Ph -ve = Polycythaemia vera (PV), Myelofibrosis, essential thrombosis (ET)

Ph-ve is associated with JaK2 mutations - which increase sensitivity to growth factors

Question 2

Polycythaemia: define

Primary causes (2), secondary causes (2)

Answer 2

Raised red cell mass, Hb, rbc count & packed cell volume

Primary causes:

• Polycythaemia vera
• familial polycythaemia

Secondary causes: increased EPO - renal Ca, hypoxia, high altitude

Question 3

Relative/ pseudo polycthaemia - waht is it? when do you get it? (2)

Answer 3

Red cell mass is normal but plasma vol reduced

e.g. burns, dehydration, diarrhoea

Question 4

Polycythaemia rubra vera (PRV) - describe

• clinical features (4)
• Ix (3)
• Rx (2)

Answer 4

A MPD where erythoid precursors dominate the BM. JAK2 mutation. Independent of normal mechs of regulation

F

• Hyperviscosity/hypervolaemia
• stroke, thrombosis, gout, retinal vein engorgment
• plethoric nose - red nose
• Blurred vision/ headache
• Histamine release > aquageni pruritis & peptic ulcers
• splenomegaly

Ix: raised Hb, HCT, (other cell counts may be raised too) low EPO

Rx - venesection, hydroxycarbadmide (aspirin may help too)

Question 5

Myelofibrosis - what is it?

Features (3)

Ix (3)

Rx (3)

Answer 5

A MPD with myeloproliferation that leads to fibrosis of BM (or replacement with collagenous tissue) Can be primary vs secondary following PRV/ ET

F

• usually elderly, pancytopenic features
• extra medullary haematopoeisis - massive splenomegaly, WL, hepatomegaly
• can present wtih budd-chiari

​Ix - tear drop poikilocytes (dacrocyte), leukoerythroblasts (primitive cells), BM - fibrosis

Rx - support with blood products, splenectomy, hydroxycarbamide, steroids, SCT

Question 6

Essential thrombocytopenia(ET) basically megakaryocytes megakaryocytes megakaryocytes (in question)

What is it?

features (3)

Ix (2)

rx (2)

Answer 6

An MPD where megakaryocytes dominate the BM

F -

• venous/arterial thrombosis - stroke/MI, gangrene, haemorrhage
• splenomegaly, dizziness, headaches

Ix - plt > 600, blood film - large plts & megakaryocyte frags, Increased BM megakaryocytes

Rx - aspirin, hydroxycarbamide, anagrelide - inhibis formation of plts from megakaryocytes