Hematology Week 3: Myeloproliferative Disorders Flashcards
Myeloproliferative Neoplasm Definition
Myeloproliferative Disorders leads to
What drives myeloproliferative neoplasm growth?
It is unregulated growth, NOT cytokine-mediated
Key types of MPN
3 listed
Polycythemia Vera (PV)
Essential Thrombocythemia (ET)
Primary myelofibrosis (PMF)
Polycythemia Vera (PV) Key features
- Overproduction of RBCs
keep in mind MPNs are stem cell disorders so platelets are increased as well but RBC are the prominent form overproduced
Essential Thrombocythemia (ET) Key Features
Prominent overproduction of platelets
Primary Myelofibrosis (PMF) Key Features
2 listed
- An initial proliferative picture with gradual BM fibrosis
- often see leukocytosis and thrombocytosis early on
Key features of MPNs Overview
Pathogenesis of MPNs
2 listed
- Tyrosine Kinase Mutations resulting in constitutive activity
- Usually in JAK2 (others are MPL and CALR)
JAK2 Point Mutation
JAK2 will be phosphorylated without EPO
MPL Receptor mutation
MPL constitutively activated without TPO
CALR Mutation
CALR is a highly conserved protein with pleiotropic roles related to its distribution in the endosplasmic reticulum and cytosol, and on the cell surface. In cellular assays, transfection of mutant CALR leads to hyperactivation of the JAK-STAT pathway
JAK2 Mutations in MPN
An acquired point mutation in JAK2 (9p) results in a constitutive cytoplasmic tyrosine kinase activity
- growth factor independence
- other proliferative/survival advantages
- V617F phenylalanine substituted for valine
JAK2 Mutation Amino Acid change
V617F phenylalanine substituted for valine
Acute Myeloid Leukemia Cell types
- Blasts predominate
- Maturation impaired/blocked
Chronic Myeloid Leukemia (CML) Cell types
- Neutrophils and other mature cells predominate
- Type of Myeloproliferative neoplasm
Polycythemia Vera Cell types
- Mature RBCs, platelets or leukocytes predominate
- myeloproliferative neoplasm
Essential Thrombocythemia (ET) Cell Types
- Mature RBCs, platelets or leukocytes predominate
- myeloproliferative neoplasm
Myelodysplasia Cell Types
- Mature Cells predominate but are reduced in number in the blood
- Cytopenia(s)
MDS/MPN/AML Blood Smears
MDS - cytopenias
MPN - Cytosis
AML - can be cytopenias, cytosis, or normal BUT ALWAYS Neutropenia, severe anemia, severe thrombocytopenia
MDS/CML/AML BM Features
MDS
CML
AML - blasts everywhere
MPN - mature cells
AML Blood Findings
- Profound cytopenias
- Variable numbers of circulating blasts
Myelodysplasia Blood Findings
Cytopenias
always at least one sustained cytopenia (anemia, neutropenia, or thrombocytopenia)
Myeloproliferative neoplasms Blood Findings
Elevated cell counts (erythrocytosis, thrombocytosis, leukocytosis (neutrophils, other mature WBCs predominate) (Sustained)