MPNs: Essential Thrombocytosis, Polycythemia Vera, Myelofibrosis,

Question 1

MPN

-pathophysiology

Answer 1

Proliferation of myeloid lineage
-RBCs, platelets, megakaryocytes, granulocytes
Can cause proliferation of all myeloid cells but classified based on dominant cell line involved

Question 2

Polycythemia vera

• pathophysiology
• presentation
• diagnosis
• management

Answer 2

JAK2 mutation => constantly active EPO receptor on stem cells => high RBC production independent of EPO

• hyperviscosity => clots
• plethoric face
• splenomegaly
• gout <= increased DNA synthesis and metabolism
• heat => itch (increaed histamine release)

High Hb, hematocrit, RBC mass
-slight increase in other myeloid cells
Low EPO
BM biopsy - JAK2

Therapeutic phlebotomy

• aspirin => reduce clots
• hydroxyurea, hydroxycarbamide => suppress BM activity

Question 3

Essential thrombocytosis

• pathophysiology
• presentation
• diagnosis
• management

Answer 3

JAK2 mutation

• increased clotting/bleeding
• splenomegaly

Diagnosis of exclusion
High platelets
BM biopsy - JAK2, increased megakaryocytes

Low risk - aspirin
High risk - aspirin + hydroxyurea

Question 4

Myelofibrosis

• pathophysiology
• presentation
• diagnosis
• management

Answer 4

Abnormal megakaryocytes produce cytokines => BM replaced by collagen

• B symptoms
• BM failure => splenomegaly (spleen tries to compensate for lack of blood cells)

Blood smear - teardrop cell
BM biopsy - dry tap, cannot get any cells, JAK2

Symptomatic - supportive transfusions, JAK2 inh
Definitive - stem cell transplant