Myeloproliferative Neoplasms

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Myeloproliferative Neoplasms

• Teresa Kraus MD
• Teresa-Kraus_at_ouhsc.edu

Modified from a lecture by Dr. William Kern
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Downloading this presentation or using any of the
diagrams, charts or photographs for any purpose
other than studying for the Blood-Hematopoiesis-Ly
mphatics course is prohibited.
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The Myeloproliferative Neoplasms (MPNs)

• Clonal proliferations of pluripotent
  hematopoietic stem cells or very early precursors
• Maturation maintained
• Increased numbers of predominantly mature,
  normal-appearing cells
• Variable predisposition to transform to acute
  leukemia or myelofibrosis

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The Myeloproliferative Neoplasms

• Chronic myelogenous leukemia, BCR-ABL1 (CML)
• Polycythemia vera (P. vera)
• Essential thrombocythemia (ET)
• Primary myelofibrosis (PMF)

P. vera, ET and PMF are sometimes grouped
together as the Philadelphia-negative MPNs
These are the 4 most common there are others.
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2008 WHO Classification of Myeloproliferative
Neoplasms

• Chronic myelogenous leukemia, BCR-ABL1
• Polycythemia vera
• Primary myelofibrosis
• Essential thrombocythemia
• Chronic neutrophilic leukemia
• Chronic eosinophilic leukemia, NOS
• Mastocytosis
• Myeloproliferative neoplasm, unclassifiable

(Rearranged)
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Myeloproliferative Neoplasms
Disease Predominant Cells

• CML Granulocytes
• P. vera Erythrocytes
• ET Platelets
• PMF Fibroblasts (driven by
  megakaryocytes)

There can be overlap between the MPNs
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Myeloproliferative Neoplasms

• Can be difficult to distinguish from each other
• Chronic myeloid leukemia has cytogenetic/molecular
  hallmark
• Philadelphia chromosome t(922)
• Others have no specific chromosomal abnormality
• Chromosomal abnormalities occur, but variable and
  not specific
• May have a recurrent molecular abnormality JAK2
  mutation

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Tyrosine Kinases

• Key regulators in signaling pathways
• Critical in cell proliferation, differentiation
  and other functions
• Many hematopoietic growth factor receptors are
  tyrosine kinases, or activate tyrosine kinases,
  or both
• Many oncogenes are tyrosine kinases

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Tyrosine Kinases Growth Factor Receptors
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Tyrosine Kinases

• Abnormalities in tyrosine kinases critical in
  MPNs
• CML BCR-ABL1 rearrangement
• Other MPNs JAK2 mutation
• JAK2 Janus kinase
• Mutation JAK2 V167F
• Found in varying proportions of other MPNs
  (excluding CML)
• P. vera gt PMF ET

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Chronic Myelogenous Leukemia

• 20 of all leukemias in U.S.
• Increasing incidence with age
• Peak age 50
• However Occurs at all ages
• Men gt Women (1.5 1)

Also called chronic granulocytic leukemia (CGL)
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CML Pathophysiology

• Philadelphia chromosome (Ph) t(922)
• ABL gene on chromosome 9 translocated to BCR gene
  on 22
• BCR/ABL1 fusion gene formed

You have to know this.
Note t(922) is not specific for CML it may
also be found in acute lymphoblastic
leukemia (ALL)
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CML Molecular Pathogenesis

• ABL Tyrosine kinase involved in cell-cell
  signaling
• BCR-ABL fusion protein More potent tyrosine
  kinase than normal ABL protein
• Different breakpoints on BCR give different
  proteins
• p210 Majority of typical CML
• p190 Most Ph-positive ALL rare CML AML

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Philadelphia Chromosome (t922)BCR-ABL
Rearrangement
ASH Image Bank
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BCR-ABL Alternative Splicing

• Different breakpoint sites on BCR gene result in
  different BCR-ABL fusion protein sizes
• p210 Protein typically seen in CML
• p190 Protein typically seen in
  Philadelphia-positive ALL
• More potent tyrosine kinase than p210
• p230 Less potent tyrosine kinase more indolent
  disease

p210 versus p190 might appear on the USMLE
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CML Phases of Disease

• Chronic Phase
• Accelerated Phase
• Blast Crisis

Occasional cases evolve into burnt out,
fibrotic phase
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CML Chronic Phase

• Most common stage at diagnosis
• Typically lasted 3-4 years
• May last lt1 year, or gt15 years
• Eventually transforms into more aggressive phase
• Directly into blast crisis, or
• Accelerated phase, then blast crisis

Natural history of the disease prior to Gleevec
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CML Chronic Phase Characteristics

• Marked granulocytosis
• Splenomegaly
• May have systemic or hypermetabolic symptoms
• Fever, night sweats, weight loss
• Hyperuricemia gouty arthritis, renal stones

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CML Chronic Phase Blood

• WBC 20,000 to gt500,000/mL
• All stages of granulocyte maturation
• Predominance of myelocytes segs
• Myeloblasts rare (usually 3 at diagnosis)
• Basophilia invariably present
• Thrombocytosis common
• May exceed 1,000,000/mL
• Mild anemia common

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CML Differential Diagnosis

• Reactive process (leukemoid reaction)
• Other myeloproliferative neoplasms
• Leukoerythroblastic reaction due to
  space-occupying lesion in marrow
• Atypical CML No Ph or BCR/ABL rearrangement

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CML Confirming the Diagnosis

• Typical CBC blood smear
• Splenomegaly
• Decreased leukocyte alkaline phosphatase (LAP)
  score
• Increased serum vitamin B12 level
• Presence of Ph and/or BCR/ABL rearrangement

Demonstration of Ph or BCR/ABL rearrangement is
mandatory
LAP score might up on exams.
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Demonstration of BCR/ABL rearrangement

• PCR-based test on blood
• Currently the usual method
• Fluorescence in situ hybridization (FISH)
• Standard cytogenetics
• Philadelphia chromosome (t(922)
• May detect variant translocations not detected by
  PCR test

Demonstration of a Ph or BCR/ABL is mandatory for
the diagnosis of CML!!
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Demonstration of BCR/ABL rearrangement
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CML Accelerated Phase

• Systemic symptoms not due to infection
• Progressive splenomegaly
• Increasing WBC not controlled by medication
• Marked basophilia (gt20)
• Thrombocytopenia (not due to medication)
• Increased blasts (5-19) in blood or marrow
• Marked marrow fibrosis

Any of these can indicate progression to
accelerated phase
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CML Blast Crisis

• Definition gt20 blasts in blood and/or marrow
• Most have myeloid phenotype
• Resemble AML
• 30 have lymphoid phenotype
• Resemble acute lymphoblastic leukemia
• Usually precursor B-cell
• Survival after onset of blast crisis 3-6 months

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CML Blast Crisis
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CML Chronic Phase Treatment

• Tyrosine kinase inhibitors (TKIs)
• Gleevec (imatinib mesylate)
• Dasatinib, nilotinib
• Hydroxyurea
• Interferon-a
• Bone marrow (stem cell) transplant

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CML Gleevec

• Inhibits BCR/ABL tyrosine kinase
• Taken orally usually well tolerated
• High hematologic response rate
• Does not appear to be curative (?)
• Resistance can develop
• Dasatinib nilotinib New tyrosine kinase
  inhibitors
• May be effective for patients who develop
  resistance to Gleevec

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Monitoring Gleevec Therapy for CML

• Periodic monitoring is required
• Quantitative PCR-based test on blood is usually
  used
• Follow absolute level of BCR-ABL transcript and
  trend up or down
• Periodic bone marrow examinations done for
  standard cytogenetics

Not for memorization
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Response to TKIs Favorable Prognostic Factors

• Rapid response to therapy
• Major cytogenetic response (marked decrease in
  Ph metaphases)
• Complete cytogenetic response is ideal
• Major molecular response (marked decrease in
  BCR-ABL transcript levels in marrow)

For information, not memorization
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Resistance to Gleevec

• Some BCR-ABL fusion genes have mutations which
  make them resistant to Gleevec
• Mutations may be present at diagnosis, or may
  develop while on therapy
• Some of these mutations sensitive to dasatinib or
  nilotinib
• A few mutations not sensitive to any currently
  available TKI

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CML Bone Marrow Transplant

• Allogeneic stem cell transplant only proven
  curative therapy
• Formerly treatment of choice for young patients
• Best done early in chronic phase
• Results worse in accelerated phase or blast
  crisis

Now largely replaced by tyrosine kinase
inhibitors as first-line therapy
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CML Treatment of Accelerated Phase or Blast
Crisis

• Accelerated phase or blast crisis treated as
  acute leukemia
• Myeloid blast crisis treated as AML
• Lymphoid blast crisis treated as ALL
• May induce second chronic phase
• Bone marrow transplant may be tried
• Overall results poor

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Polycythemia Vera Features

• Marked increase in red cell mass
• Increased RBC count, hemoglobin, hematocrit
• Splenomegaly (usually moderate)
• Predisposition to thromboembolic events
• Transformation to AML (uncommon) or burnt out
  fibrotic stage

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Definitions I

• Polycythemia Increase in RBC mass
• Erythrocytosis Increase in RBCs per unit volume
• Increase in total RBC mass (absolute
  erythrocytosis polycythemia), or
• Decrease in plasma volume (relative
  erythrocytosis pseudopolycythemia)

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Definitions II

• Primary polycythemia (P. vera)
• Independent of erythropoietin
• Secondary polycythemia EPO driven
• Physiologically appropriate
• Driven by hypoxemia
• Physiologically inappropriate
• Increased EPO due to renal cysts, tumors

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P. Vera Epidemiology

• Uncommon, but not very rare
• Slight male predominance
• Older age group Majority of cases between 60 to
  80
• Caucasians gt African-Americans

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P. Vera JAK2

• Believed that all cases of P. vera related to
  mutation in JAK2 gene
• Most JAK2-V617F
• Often homozygous
• Remainder Mutation elsewhere in JAK2 gene
• Low EPO level can be surrogate for JAK2 mutation

This is important.
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P. Vera Symptoms

• Increased blood viscosity
• Headache, dizziness, tinnitus, visual
  disturbances, dyspnea, weakness
• Splenomegaly
• Abdominal discomfort or swelling
• Thrombotic complications
• Bleeding from mucous membranes or into skin
  (ecchymoses)

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P. Vera Symptoms

• Pruritis
• Hyperuricemia Gouty arthritis, kidney stones
• Erythromelalgia Reddening, swelling pain in
  digits
• Seen with very high platelet counts
• More common in essential thrombocythemia

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P. Vera Gastrointestinal System

• Predisposition to peptic ulcer, GI bleeding,
  thrombosis of mesenteric vessels
• Massive hemorrhage from varices in esophagus,
  stomach or bowel may occur
• May have hepatic vein thrombosis (Budd-Chiari
  syndrome)

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P. Vera Central Nervous System

• Headache, vertigo, syncopal episodes, numbness or
  tingling in fingers
• Visual disturbances
• Strokes
• CNS vascular lesions most serious complication
  of PV
• 10 of deaths

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P. Vera Physical Exam

• Ruddy skin 70
• Splenomegaly 70
• Hepatomegaly 40
• Hypertension 70
• Red or dark blotches on skin
• Dilated or engorged retinal vessels

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P. Vera CBC Smear

• Hemoglobin may be up to 18-24 g/dL
• RBC count Commonly 7-10 x 106/mL
• Hematocrit Typically gt60 for men, gt55 for
  women
• Erythrocyte morphology normal
• May have mild anisocytosis microcytosis

The blood smear usually isnt very exciting
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P. Vera CBC Smear

• Leukocytosis common (50)
• Predominantly mature granulocytes
• Basophils may be slightly increased
• Thrombocytosis common (80)

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P. Vera Diagnosis

• Hemoglobin gt18.5 g/dL in men, gt16.5 g/dL in
  women, or other evidence of increased RBC volume
• Presence of JAK2 V617F or other functionally
  similar mutation
• Bone marrow biopsy showing hypercellularity with
  trilineage growth
• Serum EPO level below reference range

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P. Vera Natural History

• Median survival gt10 years (treated)
• Main problems
• Increased blood viscosity
• Predisposition to thrombosis
• Less common progression to AML or burnt out
  fibrotic phase
• Fibrotic phase resembles primary myelofibrosis

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P. Vera Treatment

• Phlebotomy is cornerstone of treatment
• Controls red cell mass by inducing iron
  deficiency
• May be only therapy required
• Others
• Hydroxyurea
• Radioactive phosphorous (32P)
• Interferon-a

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Secondary Polycythemia

• Physiologically appropriate
• Due to decreased tissue oxygenation
• Causes
• High altitude
• Pulmonary disease
• Cyanotic congenital heart disease
• Carbon monoxide poisoning
• Hypoventilation syndromes
• Abnormal hemoglobin (high O2 affinity)

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Aberrant EPO Production or Response

• Physiologically inappropriate
• Causes
• Tumors, renal cysts, hemangiomas
• Androgen abuse
• Erythropoietin abuse (blood doping)
• Familial polycythemia

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Essential Thrombocythemia (ET)

• Marked increase in megakaryocytes platelet mass
• Predisposition to thrombotic and hemorrhagic
  events
• Generally indolent course
• Transformation to acute leukemia uncommon, but
  occurs

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ET Epidemiology

• Uncommon, but not very rare
• Predominantly older population
• Men women
• Frequent occurrence in young women described in
  some series

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ET Clinical Manifestations

• Many patients asymptomatic
• Major clinical manifestations usually related to
  thrombosis
• May have bleeding (less common)

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ET Thrombosis

• Arterial gt venous
• Small vessels (arterioles) gtgt large vessels
• Any system in body can be affected
• Neurologic distal extremities most commonly
  involved

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ET Neurologic Manifestations

• Headache
• Paresthesias
• Transient ischemic attacks
• Unsteadiness, dysarthria, hemiparesis, amaurosis
  fugax, others
• May progress to definitive cerebral infarcts

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ET Small Vessel Involvement

• Microvascular events involving fingers toes
  common
• Digital pain, increased by warmth
• Gangrene of digits
• Erythromelalgia Redness, duskiness burning
  pain in extremities
• Dramatic relief with aspirin

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ET Small Vessel Involvement
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ET Thrombotic Manifestations

• Partial correlation between platelet count
  thrombotic manifestations
• Higher count associated with higher risk
• Risk factors for thrombosis
• Older age (gt60 years)
• History of previous thrombotic disease
• Smoking

Young patients with no other risk factors or
previous history of thrombotic episodes have
relatively low risk of thrombotic events
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ET Hemorrhagic Manifestations

• Tends to occur with high platelet counts (gt106
  platelets/mL)
• Bleeding is generally mild
• GI tract most common site of bleeding
• Other sites skin, eyes, urinary tract, gums,
  joints, brain

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ET Differential Diagnosis

• Reactive thrombocytosis
• Other chronic myeloproliferative neoplasms
• Pseudothrombocythemia
• WBC fragments (leukemia), schistocytes,
  microspherocytes (severe thalassemia)

Must exclude chronic myeloid leukemia (CML)!
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Causes of Reactive Thrombocytosis

• Infections
• Inflammation of any type
• Malignancy (non-hematologic)
• Trauma
• Blood loss or iron deficiency
• Splenectomy or hyposplenic state
• Hemolysis
• Rebound after thrombocytopenia of any cause

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Thrombocytosis in MPNs

• Marked thrombocytosis can be seen in any of the
  MPNs
• Platelet count cannot be used to differentiate ET
  from other MPNs
• CML is a more common cause of marked
  thrombocytosis than is ET
• CML must always be excluded in patient with
  possible ET!

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ET CBC Blood Smear

• Threshold platelet count gt450,000/mL
• May be gt1,000,000/mL
• Leukocytosis common
• Mostly mature granulocytes
• Mild basophilia occasional immature
  granulocytes may be present
• Hemoglobin usually normal
• Giant bizarre platelets on smear

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ET Treatment

• First question Who to treat?
• Older patient (gt60 years) or patient with
  previous thrombotic episodes treat
• Young (lt40 years), asymptomatic patient May not
  require treatment
• In between, asymptomatic controversial

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ET Treatment

• Control of platelet count reduces both thrombotic
  hemorrhagic complications
• Treatment options
• Hydroxyurea
• Aspirin
• Interferon-a
• Anagrelide
• Plateletpheresis

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ET Anagrelide

• Inhibits megakaryocyte maturation
• Lowers platelet coount
• Main side effects are due to vasodilation and
  inotropic effects
• Headache
• Fluid retention
• Palpitations
• May be less effective than hydroxyurea

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Primary Myelofibrosis (PMF)

• Fibrosis in marrow (myelofibrosis)
• Leukoerythroblastic reaction in blood
• Nucleated RBCs, teardrop RBCs, immature
  granulocytes
• Splenomegaly, often massive
• Extramedullary hematopoiesis

Formerly chronic idiopathic myelofibrosis (CIMF)
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PMF Pathophysiology

• Excessive production of growth factors by
  neoplastic megakaryocytes and other cells
• Growth factors stimulate fibroblast proliferation
  and production of collagen
• Fibroblasts are not part of malignant clone

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PMF Synonyms

• Chronic Idiopathic Myelofibrosis (CIMF)
• Agnogenic Myeloid Metaplasia (AMM)
• Myelofibrosis with Myeloid Metaplasia (MMM)
• Many others

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PMF Epidemiology

• Uncommon, but not very rare
• Predominantly older population
• Male female (?)
• Possible etiologic factors
• Ionizing radiation
• Organic solvents (benzene, toluene)
• No obvious underlying cause in most cases

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PMF Clinical Features

• Fatigue due to anemia
• Abdominal discomfort, early satiety due to
  splenomegaly
• Bleeding Petechiae purpura to hematemesis from
  gastroesophageal varices

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PMF CBC

• Anemia common
• WBC variable
• Leukocytosis in 1/3rd
• Leukopenia in 10-25
• Platelets Decreased in 1/3rd increased in
  10-15

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PMF Blood Smear

• Leukoerythroblastic reaction with teardrop RBCs
• Nucleated RBCs
• Granulocyte precursors, including occasional
  blasts
• Megakaryocyte fragments giant platelets

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PMF Bone Marrow

• Usually dry tap (no aspirate)
• Fibrosis (may be subtle at first)
• Cellularity Initially increased (cellular
  phase) later decreased
• Marked increase in megakaryocytes
• Osteosclerosis may develop late

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Bone marrow biopsy H E stain
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Bone marrow biopsy Reticulin stain
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PMF Differential Diagnosis

• Other MPNs
• Metastatic neoplasms Carcinoma, lymphoma
• Infections Tuberculosis, fungi
• Other granulomatous diseases
• Hairy cell leukemia
• Others

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PMF Clinical Course

• Median survival 5 years
• Younger patients without anemia may have
  prolonged survival
• Causes of death
• Infection
• Acute leukemic transformation (5-20)
• Heart failure
• Hemorrhage

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PMF Treatment

• Treatment is usually palliative
• Correct reversible factors Iron, folate
  deficiencies
• RBC platelet transfusions as needed
• Splenectomy (?)
• Interferon-a
• Stem cell transplant (experimental)

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Summary JAK2 in MPNs
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Ruxolitinib (JakafiTM)

• JAK2 inhibitor recently licensed for use in
  intermediate or high-risk PMF
• Also for fibrosis following ET or P. vera
• Decreases splenomegaly improves symptoms
• High incidence of hematologic side effects
• Does not cure disease

Will not appear on the USMLE
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CML Summary

• Marked increase in granulocytes
• Philadelphia chromosome t(922) BCR-ABL
• Predisposition to transform to acute leukemia
  (usually AML) Blast crisis
• Miracle drug Gleevec
• Inhibits BCR-ABL tyrosine kinase
• Dasatinib nilotinib are newer, more potent
  alternatives

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Polycythemia Vera Summary

• Production of excess RBCs
• Associated with mutation in JAK2 gene (JAK
  Janus kinase)
• Main risk thrombosis
• Less common acute leukemic transformation,
  myelofibrosis
• Treatment Phlebotomy hydroxyurea

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Essential Thrombocythemia

• Marked increase in platelets
• JAK2 mutation in 50 of cases
• Main risk thrombosis
• Bleeding less common
• Leukemic transformation, myelofibrosis less
  common
• Main treatments Aspirin, hydroxyurea, Anagrelide
  (?)

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Primary Myelofibrosis

• Fibrosis in marrow extramedullary hematopoiesis
  in spleen
• JAK2 mutation in 50
• Main risk Bone marrow failure (cytopenias)
• Significant risk of acute leukemic transformation
• Treatment primarily supportive (now)

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MyeloDYSPLASTIC / myeloPROLIFERATIVE NEOPLASMS
For Reference ONLY
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Myelodysplastic/Myeloproliferative Neoplasms

• New category of diseases in WHO classification
• Features of both myelodysplasia and
  myeloproliferative neoplasms
• Increased cell counts
• Abnormal cell appearances (dysplasia)

For reference only
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Myelodysplastic/Myeloproliferative Neoplasms

• Atypical (Ph-negative) chronic myeloid leukemia
  (aCML)
• Chronic myelomonocytic leukemia (CMML)
• Juvenile myelomonocytic leukemia (JMML)
• MDS/MPN unclassifiable

For reference only
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Atypical (Ph-negative) CML

• Granulocytosis fewer immature cells
• Basophilia absent
• Dysplastic changes present
• By definition, no Ph or BCR/ABL rearrangement
• Survival worse than typical, Ph1-() CML

Has no relationship to true, Ph-positive CML!!
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Chronic Myelomonocytic Leukemia

• Previously classified as myelodysplastic syndrome
• Monocytosis in blood marrow
• Dysplastic changes frequent
• WBC count may be high or low
• Hepatosplenomegaly
• Survival generally poor

For reference only
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Juvenile Myelomonocytic Leukemia

• Usually children lt 4 years old
• Boys gt girls
• Common features
• Monocytosis
• Hepatosplenomegaly
• Tissue infiltration by monocytes
• Dysplastic changes in marrow
• Erythrocytes have fetal characteristics
• Association with neurofibromatosis type 1

For reference only
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Juvenile Myelomonocytic Leukemia

• Clinical course heterogeneous
• Majority of cases aggressive
• Median survival lt 1 year
• Most die from bone marrow failure or organ
  failure due to infiltration by monocytes

For reference only