Week 6 Flashcards
Myeloproliferative Disorders are what
Clonal hematopoietic stem cell disorders that are caused by genetic mutations in HSC causing an excess of erythrocytes, granulocytes and platelets in BM , blood and tissues
Main types of MPD
Chronic Myelogenous Leukemia (CML)
Polycythemia vera (PV)
Essential Thrombocythemia (ET)
Primary Myelofibrosis (PMF)
What are the common features of MPDs
-affects middle aged or older ppl
-stable chronic disorders that turn subacute and then go into an aggressive cellular growth phase like Acute Leukemia
-can manifest a depleted cellular phase
-can have a dense cellular phase as well
seen as splenomegaly in most people
What are CML
-MPD that occurs due to single genetic translocation in pluripotential HSC
-causes overproduction of myeloid cell line with increased immature cells in neutrophil line
-seen as neutrophilia , basophilia, eosinophilia and thrombocytosis
clinically presentation as
infection
anemia
bleeding
splenomegaly
46-53 yrs
What is the clinical course of CML
if untreated it progresses into acute leukemia
3 phases without treatment
Chronic 3-4 years with <10% blasts in PB and BM - stable
Accelerated 6-18 months with 10-20% blasts in PB and BM with basophilia in PB increasing anemia
Blast phase 3-4 months >20 % blasts in PB or BM
-most symps fever and weight loss
What is the Philadelphia Chromosome (Ph)
-found in malignant proliferating clone cells, not in non hematopoietic cell
-need to identified to confirm diagnosis
-adult pts with CML have Ph in their leukemic cells
-reciprocal translocation of 9;22 that forms a chimeric fusion gene BCR/ABL1 and fusion protein BCR/ABL
-Fusion protein enhances tyrosine kinase activity
Juvenile CML for Philadelphia Chromosome negative CML in infants and very young children
Normal ABL protein function vs normal BCR1 function vs fusion protein function
Normal ABL protein responsible for tyrosine kinase activity where it activates genes control cell (signal transduction) proliferation, differentiation and apoptosis
Normal BCR1 produces serine and threonine kinase which help regulate cell growth
fusion protein affects tyrosine kinases ability to shut off which means there would be increase proliferation of myeloid cells, decreased cell adhesion to cells to BM and elimination of apoptosis
-release of immature cells into circulation
What would you see in PB of someone with CML
-leukocytosis WBC>300
-dramatic left shift with promyelo and blasts
-mostly segmented neuts, bands, metamyes and myes with eos and basos
-rare NRBC
-Plts are normal or increased can look abnormal
What will you see in BM of someone with CML
Myeloid hyperplasia - increased granulocytes and increased megakaryocytes in clusters
-hypercellularity
-M:E ratio up to 10 :1 instead of 3:1
-use a reticulin stain to demonstrate the fibrosis due to increase of reticulin fibers
What chemistry tests can you use to show possible CML
increased uric acid due to cell turnover
-2ndary gout , uric acid stones
-increased LD (LD is found in WBC)
-Increased b12 since WBC are breaking down (granulocytes are bound to B12 = if broken down then increase of B12)
What stain would you use for Chronic MPDs
LAP - Leukocyte Alkaline Phosphatase
-stain for enzyme
-LAP enzyme found in membranes of 2ndary granules of normal neuts and metamyelos
-count 100 mature neuts and grade the LAP for each
-reported as score
normal LAP 20-100
CML cells dont have LAP activity so score would be <13
Good way to differentiate between CML and leukomoid reactions because LR have normal or increased LAP score
both have MARKED LEFT SHIFT AND LEUKOCYTOSIS
how would you confirm the diagnosis of CML
demonstrating the presence of the t(9; 22) translocation
-Ph chromosome using cytogenetics, FISH or RT-PCR
you must distinguish CML from chronic MPD
What Factors determine survival time with CML
Patients that are Ph(-) have a worse prognosis than those with Ph (+) disease
-if you have other chromosomal issues
-degree of leukocytosis, thrombocytopenia, anemia
-degree of splenomegaly or hepatomegaly
-myeloid vs lymphoid blast crisis
how is CML treated
-BM or stem cell transplant
-chemo in chronic stage helps to reduce proliferating myeloids, thrombocytosis, splenomegaly, helps pt be symptom free
-Interferon-α suppresses of the Philadelphia chromosome reduces rate of progression to blast cells
-Imatinib mesylate (Gleevec) is a synthetic tyrosine kinase inhibitor which inhibits activity of BCR/ABL protein
What is polycythemia vera
-proliferation of erythroid precursors without being dependent on EPO
-can be due to JAK 2 mutation
What is the JAK 2 V617F mutation
changes Valine to phenylalanine at position 617
-this mutated gene will activate the EPO signal pathway without EPO causing upregulation of anti apoptotic protein so the PV cells dont divide quicker but they also dont die
What are the symptoms of PV
headache
vertigo
blurred vision
Ruddy cyanosis - red purple face “Rubra” vera
splenomegaly
vicious blood
What would the PB look like in PV
absolute erythrocytosis >7.0 x10^12
-increased HGB and HCT
-N/N
-N retic or little increase
-IDA develops later
moderate Leukocytosis 12.-25 x10^9
moderate thrombocytosis 450-800 x 10^9
What will you see in the lab with PV
-decreased EPO (the body is trying to stop the production of RBC so by lowering EPO less will be released from the BM but it doesnt help because the pathway is still being activated regardless) and iron
-increase RBC mass, LAP, B12
-normal or high PO2
N/N but just ALOT of RBC
LOOK AT THE MAJOR AND MINOR CRITERIA OF PV
what else can be the reason for increased HGB to differentiate PV and 2ndary erythrocytosis
-increase in hgb is relative to dehydration
-hgb increase as response to hypoxia , stress, smoked, COPD, heart disease or living at high altitude
must rule out other causes of erythrocytosis with physical and lab tests
-hypoxia causes increased red cells but thats it
PV vs Hypoxia
PV rbc mass ALWAYS increased
Hypx rbc mass CAN be increased
PV- EPO DECREASED
Hpox -EPO INCREASED
PV PO2 NORMAL
Hpox PO2 DECREASED
PV BM myelopoiesis
Hpx only erythroid hyperplasia
PV also has leukocytosis, increased plts, and splenomegaly
How to treat PV
Therapeutic Phelb
-remove 350-500 ml of blood regularly
-hct goal <45%
-can induce iron def because the iron that is being lost isnt being recycled back into the system
-Iron loss inhibits erythropoiesis delaying erythrocytosis
-increased risk of thrombosis or bleeding because plts not reduced - take low dose aspirin
-high risk of turning into acute leukemia when you use treatments other than phelb
What is the hydroxyuria treatment for pV
Alkylating myelosuppressive agents- reduce proliferation of erythrocytes and platelets
- reduction in splenomegaly & requirement for phlebotomy
-but causes increased DNA damage which can lead to acute leukemia
Jakafi (ruxolitinib) – inhibits JAK and stop anti apoptotic signals – targeted treatment
What is essential thrombocytopenia
-marked and persistent thrombocytosis
-PLTs 600-2000 x10^9
-large plt aggregates
-abnormal plt morph - giant forms and megakaryocyte fragments
-seen at 50-60 but also in women at 30
-headache, burning hands and feet , MI
mutations in PV also happen in ET but in lower frequency
What will you see in a PBF with ET
increased WBC
-neutrophilia with left shift
-RBCs N or little decreased
-plts GREATLY increased up to 5000 x 10^9/L
-giant plts or clumps vary in size and shape
-clusters near the edge of the film
What will ET look like in coagulation studies
-plt function studies are abnormal
-plt aggregation is abnormal
-normal and prolonged bleeding time
complication with hemorrhage or thrombosis if plts >2000 x 10^9
What is the WHO criteria to diagnose ET
Major criteria
PLT count >450
-BM must show significant megakaryopoiesis with large megakaryocytes with NO increase in erythropoiesis or granulopoiesis or NO left shift
-condition can meet any criteria’s for any other MPD
-must have JAK2,CALR, orMPLmutation
Minor critiera
-presence of clonal marker or absence of evidence for reactive thrombocytosis
What criteria does ET have that other MPD does not
what are other causes of reactive thrombocytosis
-diagnosis of exclusion
Normal Red cell mass
Absence of significant BM fibrosis
Negative for Philadelphia Chromosome
Found in chronic active blood loss
Hemolytic anemia
Chronic inflammation or infection
What determines a good prognosis for essential thrombocytopenia
-if thrombocytopenia can be controlled
-suppression of BM megakaryocyte production
-using hydroxy urea treatment to reduce plt count
-if it doesnt progress into acute leukemia
-but CAN progress into myelofibrosis
What is primary myelofibrosis
-when an abnormal clone of megakaryocytes stimulate the BM fibroblasts to produce collagen
-release of fibroblastic growth factors
-BM replaced with scar like material - FIBROSIS can lead to BM failure
-fibroblast proliferation causes connective tissue to replace the blood environment and releases stem cells into circulation - EXTRAMEDULLARY HEMATOPOIESIS
As with PV and ET, theJAK2V617F mutation is involved
Extramedullary Hematopoiesis what can it cause **
Hepatomegaly or splenomegaly (most pronounced)
-when cells accumulate in spleen or liver
splenic fibrosis happens later
-treat with stc transplant , JAK2 inhibitors , chemo
-does not have a good prognosis
how do you diagnose PMF
with BM
-dry tap when you get no aspirate even though you should
-BM biopsy used to diagnose
-fibrosis seen in >1/3 of biopsy
What will you see in progressive fibrosis
Myelofibrosis:
Increase in fine fibers (reticulin or type III collagen)
Myelosclerosis:
Increase in coarse, type I collagen fibers in later stages
seen with silver impregnation technique
What will you see in a PBF of PMF
-BM with pleomorphy of megakaryocytes
-immature granulocytes, NRBC, giant platelet and tears (cause rigidity of splenic sinusoids), micro megakaryocytes
