Elevated Blood Counts- Weir Flashcards
Describe the mechanism of action of the Jak2 V617F mutation.
this mutated Jak2 is associated with the EPO receptor in erythroid cells and is constitutively active. When it signals (via Stat2, ras/raf/mek/erk, or PI3K/AKT/mTOR pathways) it induces cell proliferation. This is the driving mutation at the heart of myeloproliferative disorders.
What are the diagnostic criteria for polycythemia vera?
•Elevated red cell mass >25% above normal, or Hgb >18.5d/dl (men), >16.5g/dl (women)
•JAK2 V617F mutation, or functionally similar mutation
•Minor:
BM biopsy showing panmyelosis; prominent erythroid and megakaryocyte proliferation
Low serum EPO (or normal)
Endogenous erythroid colony formation in vitro
What are the diagnostic criteria for essential thrombocythemia?
- Sustained platelet count > 450 K/uL
- BM biopsy: Meg proliferation without significant left shift nor increased erythropoiesis
- Ruling out PCV, PMF, CML, MDS, and other myeloid neoplasms
- JAK2 V617F mutation, or no evidence for reactive thrombosis
What are the diagnostic criteria for primary myelofibrosis?
•Atypical megs proliferating, with reticulin or collagen fibrosis
•Rule out PCV, CML, MDS, or other myeloid neoplasms
•JAK2 V617F mutation or rule out other cause of bone marrow fibrosis
•Minor:
Leukoerythroblastosis
Increased serum LDH
Anemia
Palpable splenomegaly
What are the diagnostic criteria for chronic myeloid leukemia (CML)?
t(9;22) seen on FISH or PCR
Name the major causes of erythrocytosis.
- Reduced plasma volume – acute conditions causing fluid loss
- Appropriately increased EPO – COPD, cyanotic heart disease, smokers, sleep apnea, drugs
- Inappropriately increased EPO – RCC, non-neoplastic renal lesions, HCC, uterine fibroma, meningioma, cerebellar hemangioblastoma, other tumors
What are complications of P. vera?
THROMBOSIS/thromboembolism, progression to AML or other malignancy, hemorrhage, myelofibrosis/myeloid metaplasia, and others
What are the treatment options for P. vera?
- Phlebotomy: median survival 14yrs
- Aspirin: lowers risk of thrombosis/CV-related death
- Hydroxyurea – reduces thrombosis, lowers Hct
- Interferon – controls platelets and Hct in most patients; may work after hydrea fails
- JAK2 inhibitors
Name the major causes of neutrophilia.
- Most common: Infection
- Inflammation
- If not sick most common: smoking or obesity
- Drugs – corticosteroids (back injections for pain), lithium
- Myeloproliferative neoplasms – CML, PCV, myelofibrosis
- malignancy
Name the major causes of eosinophilia.
•Idiopathic
•Reactive
•Hypereosinophilic syndrome = >1500, >6mo, organ damage
- Idiopathic
- Chronic – eosinophilic leukemia (CEL)
- Hematopoietic neoplasms accompanied by eosinophilia
**Also: increased eosinophils seen in MYH11-CBFB mutation in AML.
Describe the mutation and MOA of the Philadelphia chromosome.
This is the t(9;22) that results in BCR-ABL fusion protein with TK activity; turns on proliferative TFs, Bcl-2 anti-apoptosis family, and activates motility/decreases adhesion
What is the the current best therapy for CML, and what is its MOA?
imatinib - inhibits the BCR-ABL fusion tyrosine kinase protein by binding. In many cases this causes depletion of the clonal population and may be curative.
Describe the peripheral blood smear of a patient with CML.
- Elevated neutrophil count
- Left shift with myelocytosis (more than promyelocytes)
- No increase in blasts (then may be AML)
What are dacrocytes and what are they associated with?
they are teardrop red blood cells almost always seen in myelofibrosis because it is having to squeeze out through abnormal bone marrow architecture
See a teardrop cell, think bone marrow issue
True or false: myelodysplastic disorders are associated with increased cell mass, clonal origin, committed stem cell mutations, and full maturation.
False - myeloproliferative disorders are associated with these four things
In working up a patient with suspected essential thrombocythemia who is negative for a Jak2 mutation, what mutation would you screen for next?
calreticulin - this is the driving mutation in 25% of ETs (2nd place to Jak2 mutation)
What 3 MPNs can be caused by a Jak2 V617F mutation?
Polycythemia vera
Essential thrombocythemia
Primary myelofibrosis
What is the clinical presentation of primary myelofibrosis?
splenomegaly, hepatomegaly, fatigue (“these patients just feel bad”), anemia, elevated platelet count and/or leukoerythroblastic picture, thrombosis
On bone marrow biopsy what is a telltale difference between ET and primary myelofibrosis?
bone marrow biopsy shows more reticulin fibers in primary myelofibrosis
What are viable treatment options for primary myelofibrosis?
- Jak2 inhibitor - it won’t remove the clone but it will relieve the symptoms
- Allogeneic bone marrow transplant
What is the treatment for CEL/hypereosinophilia syndrome?
- imatinib
2. to treat organ damage: glucocorticoids, hydroxyurea, interferon
True or false: one of the goals of phlebotomy as treatment for P. vera is to make the patient platelet deficient.
False - phlebotomy helps P. vera patients when it makes them iron deficient, because that will keep their RBC counts under control
What is the role of basophilia in P. vera?
there is a slight basophilia seen in P. vera but not as much as in CML
What is the most common cause of death in patients with P. vera?
thrombosis