primary myelofibrosis

8/10/2019 Primary Myelofibrosis

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PRIMARY MYELOFIBROSIS

BY

DR. EMMANUEL E. EKANEM

DEPARTMENT OF HAEMATOLOGYUUTH, UYO.

November 17,2014


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OUTLINE

Introduction

Epidemiology

Classification

Aetiology & Pathogenesis

Pathology

Clinical and Laboratory Features

Diagnosis and Prognostic Features

Advances in Management Conclusion

References


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Introduction

Primary Myelofibrosis is a clonal myeloiddisorder characterized by anaemia,splenomegaly, immature granulocytes,

marrow fibrosis and osteosclerosis. Tear drop Poikilocytes and

leukoerythroblastosis with increased CD34+cells in the peripheral blood film.

A rare haematologic malignancy classified asone of the Ph negative MPNs (PRV, ET)


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Epidemiology

Annual incidence is put at 0.41 to 1.46 per100,000 population

2.7% (2010, Benin)

None recorded in UUTH After the age of 50 years

Median age at diagnosis is approx. 65 to 70 years

Can occur from Neonatal period to the ninth

decade of life When it occurs in children, it is in the first 3 years

of life


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Contd

F:M of 2:1

In adults F:M is 1:1

Can cluster in families ()


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Contd

Classification

The IWG-MRT subdivided MF into 2 main

groups:

Primary: de novo disease accounting for 90%

of cases

Secondary: transformed from PRV, ET, orCML


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Aetiology

The exact aetiology of primary MF isunknown, however, it has been linked withseveral agents such as

Ionizing radiation Benzene

Toluene

thorium dioxide: high incidence associatedwith thorium-based radiographic contrastmaterials


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Contd

Atomic bomb exposure

Genetic abnormalities: current understanding

suggests that evolution of primary MF is

secondary to acquired genetic abnormalities

that target the haemopoietic stem cell in 40%-

60% of patients at the time of diagnosis.


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Contd

Genetic abnormalities include:

i. Interstitial deletions of ch. 13q and 20q

ii. Trisomy 8 iii. Abnormalities of ch. 1, 7, and 9

iv. Mutations involving the gene encoding

Janus Kinase-2 (JAK2 V617F) Involvement of chromosomes 5,6,7,9,13,20,21

is frequent


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Contd

(JK2), at position V617F found in 5065% of

patients with primary MF, 96% of PRV, and

55% of ET

iv. Myeloproliferative Leukaemia virus

oncogene/thrombopoietin receptor (MPL),

and

v. Loss of function mutation (LNK)


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Pathogenesis

Mutations in JAK2, LNK result:

a) Activation of JAK/STAT (signal transducer and

activator of transcription) pathway which

promotes transcription of

i. Proliferative and anti-apoptotic genes

ii. Inflammation which results in disturbed

cytokine production which causes the release

of growth factors


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Contd

that:

-stimulate fibroblasts proliferation,

-local fibrosis, and later -osteosclerosis, and eventually

-BM failure

b) Cytokines released can also stimulate theJAK/STAT


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Contd

b)Fibrosis: the secondary BM fibrosis results

from non-clonal fibroblastic proliferation and

hyperactivity induced by growth factors

abnormally shed from clonally expandedmegakaryocytes

c) Others: there is increased number of

stroma cells, the level of extracellular matrixproteins, increased


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Contd

resulting in the propagation of the cycle

including

Platelet-derived growth factor (PDGF)

Basic fibroblast growth factor (bFGF)

Transforming growth factor beta (TGF-)

Vascular endothelial growth factor (VEGF) Tumour necrosis factor alpha (TNF-)


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Contd

angiogenesis and osteosclerosis.

i. Fibroblast proliferation: PDGF and

Calmodulin

ii. Collagen synthesis: TGF-

iii. Angiogenesis: VEGF and bFGF

iv. Osteogenesis: TGF- and bFGF


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Clinicopathological features

BM fibrosis: this is the hallmark and

contribute to the impaired haematopoiesis

that leads to the severe anaemia

Marked splenomegaly

Extramedullary haemopoiesis

Severe constitutional symptoms


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Clinical features

Generally, clinical features of MF is classifiedeither as spleen-related or non-spleen related

a) Spleen-related: reported in 60% to 80% of

cases -abdominal discomfort due to massive

splenomegaly

-abdominal pain due to ischaemia or infarction(Spleen)

-early satiety


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Contd

-pain under the ribs

-portal hypertension and variceal bleeding

-ascites b) Non-spleen related: reported in about 60%

of cases

-fever, night sweat, weight loss, -pruritus


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Contd

-fatigue, bone and muscle pain

These constitutional symptoms are mediated

by the released cytokines

c) cytopenia: about 30% of patients may

present with anaemia at diagnosis and it

varies from mild to transfusion-dependent


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Contd

Miscellaneous:

-hepatomegaly, ascites, pleural effusion

-lymphadenopathy, nerve/cord compression -osteosclerosis

-thrombohaemorrhagic complications

secondary to leukocytosis and/orthrombocytosis


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Laboratory features

FBC+Peripheral Blood Film:

RED CELLS

Normocytic-Normochromic anaemia present in most cases

Anisocytosis & poikilocytosis are constant findings.

Tear drop-shaped red cells (dacrocytes) in every oilimmersion field.

nRBC in blood film of most patient. Average of 2% (Range 0-30%).

Mild reticulocytosis

Hb conc. In a series of patients is approx. 9.0 to 12.0g/dl


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Contd

Anaemia may be worsened by plasma volume

expansion and higher MCV in patients with

enlarged spleen.

In some Patients haemolysis may be present

Polychromatophilia and very elevated

reticulocyte count.


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PBF


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Contd

WBC

Mildly elevated TWBC count due to

granulocytosis

Mean TWBC count maybe 10 to 14x109/L

Small proportions of myelocytes &

promyelocytes in PBF

0.5% to 2% blast may be found in blood film


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Contd

At diagnosis blast can range b/w 0-20%

Hypersegmentation and Hyposegmentation maybe present.

Abnormal granulation of neutrophils MAP scores may be elevated in 25% of patients

or deceased in 25% of cases

Basophils is slightly increased

Neutropenia is present approx. 20% of cases attime of diagnosis


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Contd

PLATELETS

Mean platelet count at diagnosis is 175 x109/L to580 x 10/L. But may be up to 3125 x109/L.

Elevated in 40% of cases Mild to moderate thrombocytopaenia is present

in 1/3 of patients

Characteristically there is presence of giant

platelet and abnormal platelet granulation Presence of megakaryocytes in systemic venous

blood


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Contd

10% present with pancytopaenia because of

severe impairment of haemopoiesis affecting

all cell lines, coupled with sequestration in

massively enlarged spleen.

Pancytopaenia is usually associated with

intense marrow fibrosis


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Contt

An increase in blood CD34+ cells which is very

characteristic of primary MF.

The conc. Of CD34+ cells correlates with the

extent of disease and disease progression.

> 15 x 109/L CD34+ cells is Diagnostic

>300 x 109/L CD34+ cells have rapid

progression.


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Contd

Endothelial progenitor cells are significantly

higher in Primary MF than in normal subjects

(CD+CD133+ & VEGFR2 Positive cells)

Decreased CD3+,CD4+,CD8+&CD3-/CD56+ T-

cells due to mild lymphopoiesis is the rule.


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Bone Marrow Findings

In Fibrotic Phase; BMA may be difficult, and

often yielding no aspirate (dry tap) due to

fibrosis.

Trephine Biopsy:

- Fibrotic Hypercellular marrow

- Decreased, normal or increased erythoid cells

- There is granulocytic and megakaryocytic

hyperplasia


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Contd

Granulocytes may show hyperlobulation &

hypolobulation of nucleus

Nuclear blebs

Nuclear-cytoplasmic maturation asynchrony

Clusters of blasts & CD34+ cells are present

Increase micro vessel density in 75% patients


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Contd

Silver Stain: shows increased reticulin fibers.

H&E: Stain: Shows mild collagen fibrosis.

Occasionally fibrosis is extreme. Maybe more

evident using Gomori Trichrome stain that

stains collagen green.


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Marrow section

Silver impregnation stain:marked increase in

argentophilic fibers

representing collagen type III

(reticulin)


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Marrow section

Collagen fibrosis withextensive replacement of

marrow with swirls of

collagen fibers.


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Contd

In pre-fibrotic phase: The marrow has no or

slight reticular fibrosis

Hypercellular marrow

Erythropoiesis may be slightly increased

Increased late neutrophil precursor

(myelocyte, metamyelocytes & bands)

Myelocytes and CD34+ cells are inconspicuous


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Contd

The hallmark of this phase is increased and

abnormal megakaryocytopoiesis

Clusters of megakaryocytes

Large megakaryocytes admixed with small

megakaryocytes

Bare megakaryocyte nucleus


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Bone marrow Slide

Bone marrow slideat low power:

Shows

hypercellular

marrow with

increased number

of hypolobular

megakaryocytes.


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MRI

Hypodensity of T1-weighted & T2 weighted

images due to increase cellularity & fibrosis.

Patchy or diffuse osteosclerosis is a common as

are sandwiched vertebrae so called because ofthe marked radio density of superior and inferior

margins of the vertebral body.

MRI can also show the periosteal reactions thatusually occur in the distal femur, proximal tibia

and ankle.


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Contd

Sodium fluoride positron emmission

tomography can be virtually specific for

osteosclerosis of primary MF.


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chemistry

Increased Uric acid, LDH,bilirubin, alkalinephosphatase & HDL are frequently seen.

Reduced albumin, and cholesterol also

frequent Calcium levels or

thrombopoietin and IL-6

IL-2 receptor Vascular Endothelium Growth Factor

Urinary calmodulin is up to 3 times of normal


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Diagnosis

Differential diagnosis of MF should include BM

fibrosis associated with both neoplastic and

non-neoplastic conditions, including CML,

CMML, MDS, Lymphomas, AML,carcinomatosis

However, the presence of specific cytogenetic

abnormalities JAK2 or MPL mutations rule outreactive BM fibrosis, while


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c) The presence of trisomy 9 or 13q- deletion

suggests MF

d) WHO Criteria: for accurate diagnosis, there

are major and minor criteria that must be met

by patient

Major Criteria: all these must be present

1. Megakaryocyte proliferation and atypia:

responsible for reticulin or collagen fibrosis


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Contd

2. Does not meet the criteria for other

myeloid disorders (PRV, CML, MDS, ET)

3. Presence of clonal markers such as

JAK2V617F, MPL: there should be no evidence

of secondary BM fibrosis

Minor criteria: at least 2 of these are


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Minor criteria: at least 2 of these are

required

1. Increased serum LDH levels

2. Palpable splenomegaly

3. Leukoerythroblastosis

4. Anaemia


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Prognosis

MF is a progressive disease, with its prognosis

depending on several factors.

The IPSS estimates survival from the time of

diagnosis, using the following risk factors:

Age 65 yrs or older

Anaemia, with Hb level


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CONTD

Presence of constitutional symptoms

5. Leukocytosis, with WBC of > 25,000/cmm

6. Circulating blasts of at least 1%

The IWG-MRT proposed a scoring system

based on number of these factors present and

categorized patients into 4


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Contd


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Prognosis contd

IPSS has now been updated to dynamic IPSS

(DIPSS) using the same prognostic factors and

can be used to estimate survival at any point

during the course of the disease

The DIPSS has been upgraded to DIPSS-plus by

incorporating 3 additional factors including:


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Contd

Blood transfusion dependency

Thrombocytopenia of < 100,000/cmm, and

Presence of unfavourable karyotype (Trisomy

8, monosomy 7 or 7q-, inv 3, 11q23, 12p-

Based on this additional factor, patients canbe group into 4 prognostic categories:


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Contd

Other factors that may contribute to survival

include:

Monocytosis of > 1 x 109/L

JAK2 mutation

Male sex

Hepatomegaly


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Treatment

Allogeneic Stem Cell Transplantation

Signal Transduction Inhibitors

JAK inhibitors

Symptomatic/Supportive treatment


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Treatment

1. Allogeneic Stem Cell Transplantation

Any treatment that excludes ASCT is not

curative This will, however, be used in selected high-

risk eligible patients

This is currently the only potential cure forpatients with DIPSS-plus intermediate 2 andhigh-risk disease if


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Contd

is younger than 40 to 50 years

Patients with DIPSS-plus low or intermediate-1

risk disease may not be considered for ASCT

because the risk of conditioning regimen may

outweigh the benefit that is derivable.


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2. Signal Transduction Inhibitors

i. Imatinib mesylate

Its use is based on its inhibition of PDGF-

mediated signalling

It also ameliorate BM fibrosis and microvessel

density

It is effective in restoring megakaryocyticdifferentiation


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Contd

and thus, effective in the treatment of

thrombocytopenia

ii. Farnesyl transferase inhibitor

Can cause significant reduction in

splenomegaly

Has negligible effect on anaemia

Myelosuppression is the main side effect


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Contd

3. JAK Inhibitor

The discovery of the role of JAK/STAT pathway

in the pathogenesis of MF has made targeting

JAK2 a therapeutic goal

Ruxolitinib is the only JAK inhibitor approved

US FDA for use

It is an oral formulation


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Contd

JAK1 and JAK2 inhibitor for intermediate and

high-risk MF

It has been found to cause significant

reduction in splenic size in 35% of patients

The most common side effects are

thrombocytopenia and anaemia

Dose to be given is limited by platelet count:


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Contd

Platelet of

>200,000/cmm give up to 20mg bid

100,000200,000/cmm give 15mg bid


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Contd

4. Symptomatic/Supportive

a) Splenectomy

Has no clear effect on patients survival,

disease course or intramedullary

manifestation of the disease

However, significant decrease in symptoms

was observed in 30% to 50% of patients


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Contd

Complications rates are high, hence, candidate

for splenectomy should be carefully chosen

Indication for splenectomy include:

1. Substantial and refractory symptomatic

splenomegaly

2. Refractory cytopenia, particularly, anaemia


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Contd

3.Evidence of portal hypertension

4.Hypermetabolic symptoms

i. Conditions: patients should be surgically

stable

ii. Must have failed at least one medical

therapy (including JAK inhibitor)

iii. Good performance status

iv. Have life expectancy of more than 1 year


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Contd

b) Radiotherapy

Patients with extramedullary haemopoiesis

are sensitive to radiation

It is palliative in patients not eligible for

splenectomy, or

Have short expected survival


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Contd

c) Immunomodulating agents

Thalidomide, Lenalidomide, andPomalidomide used alone or in combination

with Corticosteroids are good at amelioratingcytopenias

i. Thalidomide:

significant response in anaemia (62%),thrombocytopenia (75%), and splenomegaly(19%) have


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Contd

been reported with low-dose combined with

prednisolone

Neuropathy, DVT, constipation are the main

side-effects

ii. Lenalidomide:

response rate of 22% for anaemia, 33% for

splenomegaly, and 50% for thrombocytopenia.

Prednisolone did not improve the outcome


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Contd

Reduce fibrosis in patients with concurrent 5q-

deletion

Milder myelosuppression

iii. Pomalidomide:

Improve anaemia in 20% to 30% of patients in

low dose

No substantial BM suppression or neuropathy


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Contd

d) Cytoreductive agents

i.Hydroxyurea: useful in the control of

splenomegaly (50%), leukocytosis, and

thrombocytosis

ii.Melphalan: reduces spleen size in 66% of

cases. However, acute leukaemia is the main

side effect


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Contd

iii. Interferon-:

Has cytoreductive effect similar toHydroxyurea

It inhibits Megakaryocyte and Fibroblastproliferation, and controls Collagenproduction

It also inhibits fibrogenic cytokines such asTGF-1 and PDGF in patients withhyperproliferative features


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Contd

However, not well tolerated due to toxicity,particularly cytopenia

iv. Cladribine gives 50% response in splenomegaly,

thrombocytosis, leukocytosis, and anaemia,

respectively Myelosuppression and GIT upset are its limiting

toxicity


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Contd

v. Azacytidine

Gives 21% response rate for splenomegaly

Requires frequent visits for administration

Myelosuppression is the main side effect


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Contd

Management of anaemia

Common; and tend to progress over the

course of the disease

Aetiology is multifactorial including

hypersplenism, BM fibrosis, ineffective

haemopoiesis, and haemolysis

Androgens, Corticosteroids, and Erythropoietin

are used


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Contd

in treatment

Androgens

Preparations containing different compounds

such as Fluoxymesterone, Nandrolone,

Oxymethalone, Testosterone, Enanthate, and

Danazol have shown improvement in 30% to

40% of cases


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Contd

Danazol is particularly useful in correcting

thrombocytopenia

2. Erythropoietin

In the absence of splenomegaly,

erythropoietin stimulating agents (ESAs =

Epoetin alpha, Darbepoetin alpha) are useful

in patients with Hb < 10mg/dL


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Contd

Transfusion-dependent patients or those with

Epo levels higher than 125U/L are unlikely to

benefit from ESAs

Thrombocytosis and Thrombosis

1. Anagrelide hydrochloride

An oral preparation approved by the US FDA

as a first-line


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Contd

agent for the control of thrombocytosis

associated with MF

Chronic exposure to Anagrelide results in a left

shift in megakaryocyte maturation andinhibition of endoduplication

This causes a decrease in ploidy and cell size,

and an increase in the number ofpromegakaryoblasts


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Contd

Its effects on megakaryocyte is important as itprevent the secretion of cytokines that

promote fibrosis and osteosclerosis However, the drug has no impact on BM

fibrosis or on the production of profibroticcytokines, TGF- and PDGF

2. Aspirin and HU are also useful in preventingthrombosis


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Differential Diagnosis

CML

MDS

Primary Thrombocythaemia

Hairy Cell Leukaemia Hepatic Disease

Primary Immune Myelofibrosis

Sporadic Idiopathic or Familial PulmonaryHypertension

Metastatic carcinoma of breast or prostate


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Contd

Or disseminated mycobacterial infection Others include:

Mastocytosis

Angioimmunoblastic Lymphadenopathy

Angiosarcoma

Lymphoma Multiple Myeloma

Renal osteodystrophy

Hyperthrophic osteoarthropathy

Gray Platelet Syndrome

SLE

Polyarteritis nodosa

Hypereosinophilic syndrome

d


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Contd

Kala azar PrimarThrombocytopaenic Purpura

TTP

Neuroblastoma

Giant Lymph node hyperplasia

Vit. D def. rickets

Acute Promyelocytic Leukaemia

Langerhans cells histiocytosis Malignant histiocytosis

/ l


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Summary/Conclusion

Primary Myelofibrosis is one of the several

disorders in the spectrum of clonal myeloid

diseases, malignant diseases that originate in

the clonal expansion of a single neoplastichaematopoietic mutipotential cell. About 50%

of cases have a mutation in the Janus Kinase 2

gene. Characterized mainly by anaemia,thrombocytosis, and splenomegaly with an

overall median survival of 5 years.

f


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References

Lichtman MA; Beutler E; Kipps T; Seligschn V;Kaushnsky K; Prchal J; Chapner B; Wilson Wand Supko J Williams Haematology, 8thedition. The Mcgraw-Hill Companies.

Shirish M. Kawthalkar. Essential ofHaematology. Jaypee Books.

A.V. Hoffbrand et al. Blackwell publishing:

Essential Haematology, 6thed.

www.accessmedicine.com
http://www.accessmedicine.com/http://www.accessmedicine.com/


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