Pediatric AML including myeloid proliferation in Downs syndrome,

Infantile acute leukemias, and childhood MDS

P.Rajaguru

Dr. Shano Naseem

Pediatric AML

Pediatric AML

• Less common in pediatric population than adults. More common in adolescence and a peak during the neonatal period.

Clinical presentation

• Variable • Hyperleukocytosis • Organomegaly• Respiratory distress• 25-30% develop skin lesions (Leukemia Cutis)

– 50% of cases are initial sign– 10% of cases occur in the setting of normal BM

• CNS involvement• lymphadenopathy

Predisposing FactorsInherited Predisposition Syndromes• Inherited Marrow Failure and Chromosome Instability Syndromes:

Fanconi anemia, dyskeratosis congenita, bloom syndrome, ataxia telangiectasia.

• Defects in Genes Regulating Differentiation and Cell Proliferation Pathways:

1) Congenital amegakaryocytic thrombocytopenia- inherited mutations in the thrombopoietin receptor (c-mpl),

2) familial platelet disorder -CFFA2,

3) Severe congenital neutropenia (Kostmann syndrome)- treated with G-CSF,

4) Shwachman-Diamond syndrome,

5) Diamond-Blackfan anemia –RPS 19,

6) Neurofibromatosis type 1 and Noonan syndrome activation of the RAS gene pathways. Germline mutations of PTPN11 have been shown to lead to Noonan syndrome and JMML.

• Twins and Familial Cases: Transplacental transfer. Transmission rates have been reported to be 20 to 30% (some investigators ∼have concluded transmission rates may approach 100% )

• normal twins- followed every ~1 to 2 months until 2 years of age ∼with physical examinations and peripheral blood cell counts.

• The risk of developing acute leukemia for nonidentical twins has been estimated to be a two- to fourfold increase until 6 years of ∼age

Acquired Predisposition• Up to 20% of patients with severe aplastic anemia treated

with immunosuppressive agents• Environmental Factors: Prenatal exposure to chemical

genotoxic agents, prenatal alcohol consumption, maternal ingestion of topoisomerase II inhibitors

AML subtype

• FAB subtypes M5 (acute monocytic leukemia) and M7 (acute megakaryoblastic leukemia) are significantly more common in younger children

Treatment

• Remission-induction regimen, followed by a course of consolidation therapy, and, subsequently, an intensification course, which may include hematopoietic stem cell transplantation (HSCT).

Infantile acuteleukemias

Infant Leukemia (< 12 ms of age)• Leukemia is the second most

common malignancy in

the first year of life• Annual incidence rate ~ 40

cases per million infant in the US

• There are ~126 new cases of

Infant ALL and ~67 new cases of infant AML per year

Congenital leukemia (birth to 4 wks of life)• <1% of all childhood leukemia • Incidence rate is 1 per 5 million birth• occur within 4-6 wks of birth• Only 200 cases been reported in the literatures• AML is the most common type (64%) than ALL (36%)• Retrospective identification of leukemia-specific

fusion genes (e.g., MLL-AF4, TEL-AML1) in the neonatal blood spots and development of concordant leukemia in identical twins indicate some leukemias have a prenatal origin.

Greaves MF, Maia AT, Wiemels JL, Ford AM: Leukemia in twins: Lessons in natural history. Blood 102:2321, 2003

Diagnostic criteria

INFANTILE LEUKEMIAS

EPIDEMIOLOGY

• Overall incidence- 36 cases/ million live births.

• The ratio of ALL to AML in infancy is reported to be between 1 and 1.5 whereas the percentage of ALL cases is about four times that of AML in older children (less than 15 yrs)

• In infants (1st year of life )

AML- comprise 6-14% of pediatric AMLs

ALL- comprise 2.5-5% of pediatric ALLs.

BLOOD, JULY 2000 VOL 96 (1) 24-33 J Natl Cancer Inst Monogr 2008;39: 83 – 86

EPIDEMIOLOGY• Sex

• White infants experience about a 50 % higher risk than Black infants

• Highest rates of infant leukemias- Japan, Australia and Los Angeles.

PNAS April 25, 2000 vol. 97(9)4411–13.

Infants Older children

ALL F>M M>F

AML F>M M=F

Clinical Presentation Of Infantile Leukemia • Variable • Hyperleukocytosis • Organomegaly (70-80%) • Respiratory distress• Hydrops Fetalis (jaundice, pleural effusion, ascitis)• 25-30% develop skin lesions (Leukemia Cutis)

– 50% of cases are initial sign– 10% of cases occur in the setting of normal BM

• CNS involvement,(50%)• lymphadenopathy (25%)

Molecular Basis of Pediatric Leukemias

~80% of cases of infant ALL and ~80% of FAB M4/M5 AML in infants and young children

ALL

Presentation and Natural History• At initial diagnosis, ALL in infants is characterized by

-white blood cell count of >50 x 109/l-frequent hepato-splenomegaly, and -involvement of the CNS (14 to 41% compared with 5% in older children

• ALL with MLL rearrangement is the most common leukemia in infants <1 yr of age.

ALLMorphology & immunological phenotype• FAB morphology is L1 more often than L2 .• The immunophenotype is usually that of immature B-lineage

precursors and is characterized by a lack of CD10 expression and the coexpression of myeloid-associated antigens.

• These findings suggest that the classic form of infant ALL originates in a stem cell that has not fully committed to lymphoid differentiation.

• T-cell ALL accounts for up to 20% of ALL.

Cytogenetics

IMMUNOPHENOTYPE

Infant AML

AML with MLL rearrangement

Presentation and Natural History• Hepatosplenomegaly, and high white blood cell

count at diagnosis.• High percentage of CNS involvement.• Leukemia cutis and chloromas and DIC are more

common on infant AML than ALL.

AML

Morphology & cytochemistry• Majority of AML in infants are of FAB M4 or FAB M5

morphology.• Monoblasts and promonocytes are typically

predominate.• These cells usually show strong positive NSE and

often lack MPO reactivity.

BM P-421/08

Immunophenotype

• AML with MLL translocation are associated with strong expression of CD33, CD65, CD4 and HLA-DR, while expression of CD13, CD14 and CD34 are often low.

• Most adult AML cases with 11q23 abnormalities express markers of monocytic differentiation like CD14,CD4,CD11b,CD11c, CD64,CD36 and lysozyme.

Cytogenetics

• 60% of infant AMLs have an MLL gene abnormality.• The t(9;11) translocation is the most common translocation in

AML in infants, followed by the t(11;19), t(10;11) and t(6;11).• The FAB M4 or M5 cases without MLL gene translocation

include

- leukemias with inv(16), which are FAB M4 with eosinophilia (FAB M4eo)

-leukemias with monosomy 7

-random cytogenetic abnormalities, or

-normal karyotypes

Infant AML with t(1;22)

• AML with t(1;22) RBM15-MKL1 is an AML generally showing maturation in the megakaryocyte lineage.

• Representing <1% of all cases.• Most commonly occurs in infants without down

syndrome, with a female predominance.

WHO 2008

Presentation

• Clinically pts present with organomegaly, anemia, thrombocytopenia and elevated white cell count.

• The PB and BM blasts are similar to those of acute megakaryoblastic leukemia of AML , NOS

• Cytochemical stains for SBB and MPO are consistently negative.

Immunophenotype

• The megakaryoblasts express CD41,CD61 and less frequently CD42.

• The myeloid associated markers CD13 and CD33 may be positive.

• CD34, CD45 and HLA-DR are often negative.

Cytogenetics

• In most cases t(1;22) occurs as a sole karyotypic abnormality.

• Recent studies found that these pts respond well to intensive AML chemotherapy with long disease free survival.

Mixed phenotype acute leukemia

• This is a rare leukemia that is relatively common in infancy with MLL rearrangements.

• Many cases of ALL with MLL translocations express myeloid-associated antigens,but these should not be considered MPAL.

• Most commonly these leukemias display a dimorphic blast population, with one population clearly resembling monoblasts and the other resembling lymphoblasts.

• However, in other cases they appear only as undifferentiated blast cells.

WHO 2008

Immunophenotype

• In the majority of cases it is possible to recognize a lymphoblast population with a CD19+,CD10- pro B-immunophenotype.

• Along with a separate population of myeloid lineage, usually monoblastic cells can be demonstrated.

• All cases have rearrangement of the MLL gene with most common translocation t(4;11).

• This is a poor prognosis leukemia.

Molecular pathogenesis

• The most common genetic events occurring in infants < 12 months, both in ALL and AML, are the rearrangements of the MLL gene.

• By genetic analysis, it is estimated that nearly 60% of infant AMLs and 75% – 80% of infant ALLs have an MLL abnormality in their leukemia cells.

• Has many fusion proteins • Most common are AF4 on ch 4q21, ENL on ch 19p13

and AF9 on ch 9p22.

Int J Hematol. 2005;82:9-20

• MLL (a/k/a ALL-1,HRX) is located on chromosome 11 band q23 and is a frequent target of chromosome translocations in hematopoietic malignancy.

• MLL gene fusions are particularly prevalent in 2 situations:

Infant leukemia Treatment-related secondary leukemia (mostly AML).

• The existence of MLL fusion is usually an indicator of poor prognosis.

• One of the critical functions of MLL appears to be to

maintain expression of Hox genes such as HoxA9 and

HoxC8, which are themselves essential regulators of

development.

MLL FISH Green = 5’ MLL Red = 3’ MLL

Etiopathogenesis

• There is no doubt that the risks of developing early acute leukemia are modulated by complex interactions between inherited predispositions, environmental exposure to damaging agents and chance events.

• The molecular epidemiological approach to genetic studies has suggested the concept that most, if not all, childhood acute leukemia cases originate in utero.

Brazilian Journal of Medical and Biological Research (2007) 40: 749-760

Risk factors

Mechanism of leukemogenesis

• The mechanisms of leukemogenesis in early infancy are related to the fact that the growing fetus is more sensitive to the effects of potential DNA damage insults during the early stage of pregnancy.

• Many studies supports the theory that the exposure of pregnant women to substances that inhibit topoisomerase II could be a critical event in the development of leukaemia in infancy.

DNA topoisomerase II inhibitors

• One mechanism leading to ALL1/MLL/HRX translocations might be chromosomal breakage induced by topoisomerase- II inhibitors within the ALL1/MLL/HRX gene.

• While another could be represented by mistakes in DNA-repair mechanisms.

• This hypothesis is supported by Aplan et al showing that topoisomerase-II–inhibiting drugs cleave double stranded DNA at a site in ALL1/MLL/HRX exon 9 both in vivo and in vitro.

• DNA topoisomerase II inhibitor therapy-related leukemias are predominantly seen in AML than ALL.

• If these exposures are so common, why is infant leukemia so rare?

• The first answer may lie in the timing of exposure • Secondly, there is growing evidence that

polymorphisms in genes involved in the metabolism and detoxification of certain chemicals are important in etiology.

J Natl Cancer Inst Monogr 2008;39: 83 – 86

Maternal alcohol intake;• The mechanism is explained by the ethanol induction

of microsomal enzymes, such as cytochrome P450, which subsequently activate pre-carcinogens .

• The same study showed that paternal smoking one month prior to pregnancy was associated with an increased risk.

J Natl Cancer Inst 1996; 88: 24-31.

High-birth weight• Since insulin-like growth factor-1 is important in

blood formation and regulation and has been shown to stimulate the growth of both myeloid and lymphoid cells in culture.

• It was postulated that high levels of insulin-like growth factor-1 might produce large babies and contribute to the development of leukemia.

Cancer Causes Control 1996; 7: 553-559.

Differential diagnosis

1.Other causes of Leukemoid reactions such as feto-maternal blood incompatibilities, intrauterine infections (in which dermal hematopoiesis can persist), such as syphilis, rubella, cytomegalovirus, toxoplasmosis, and herpes simplex infections.

2.TMD of down syndrome.

Myeloid proliferation in Downs syndrome

Down syndrome

• Frequency of Down in general pediatric population:

1 per 700 live births

• ALL in 5-30yr age group: 12 fold increase

• ALL in <5yr age group: 40 fold increase

• AML in <5yr age group: 150 fold increase

Hematological abnormalities in Down syndrome

TRANSIENT ABNORMAL MYELOPOIESIS

• Synonyms :Transient myeloproliferative disorder, Transient leukaemia

• Haematological disorder virtually confined to Down syndrome

• Presents during fetal life or in the neonatal period

TAM : incidence

• Using the clinical and hematological criteria 10% of all newborns with Down syndrome have TAM

Hematological and clinical features of TAM in Down syndrome

TAM : hematological findings

• Haemoglobin level and neutrophil count are usually normal in TAM,

• Platelet count is often abnormal—both thrombocytopenia and thrombocytosis are reported.

• Blood film may show nRBC, giant platelets and megakaryocyte fragments

TAM

CYTOCHEMISTRY OF TAM BLASTS

• positive for acid phosphatases and NSE • negative for MPO,SBB, CAE and PAS

FLOW CYTOMETRY OF TAM BLASTS

• Immature markers : CD34, CD56,CD117• Early myeloid :CD13, CD33• HLA-DR : 30%• Megakaryocyte : CD41, CD61 • may express CD7 (a T-cell antigen)• Dim CD4 positivity• CD34 negative in 50% cases and CD41&CD56

negative in 30% cases

The importanceof TAM

• TAM can therefore be considered as a leukaemic or ‘‘pre’’-leukaemic syndrome

• Potential to transform into an acute leukaemia known as myeloid leukaemia of Down syndrome (ML-DS)

• Estimated incidence of transformation into ML-DS: 20–30% of babies with TAM, although the exact frequency is not known

TAM : mutations

• neonates with TAM - mutations in the key megakaryocyte transcription factor GATA1

Diagnostic difficulty

• Phenotypically normal mosaic Down syndrome

• Only clue to the diagnosis is a blood film picture typical of TAM

• Therefore any infant with blood film abnormalities suggestive of TAM should have cytogenetic analysis to look for trisomy 21.

TAM : COURSE OF DISEASE

Refer to pediatric hematologist

• Appropriate tests • Specialised intervention• Follow-up: for conversion into ML-DS

Poor prognostic parameters that may necessitate treatment with low-dose cytarabine

in DS patients with TMD

PROGNOSIS

• Severe liver disease, with fibrosis due to the production of megakaryocyte-derived growth factor from blast cells, has a poor prognosis and may not respond to treatment.

• Despite resolution in most cases of TAM, up to 20% of infants who present to haematology centres still die of disease

Acute myeloid leukaemia in Down syndrome

• Markedly distinct from the acute myeloid leukaemia that develops in children without Down syndrome

• Usually presents :1-4 years (median-1.8 years)

• 20–30% of infants with TAM develop ML-DS either by overt progression or more commonly, after an apparent remission

INCIDENCE

• 1-2% of Down have ML-DS within first 5 yrs of life

ANTECEDENT MDS

• An antecedent myelodysplastic phase -70%

• Anaemic and thrombocytopenic with dysplastic changes in erythroid cells and megakaryocytes

• Marrow often becomes increasingly difficult to aspirate due to hypercellularity and myelofibrosis

ML-DS :BLOOD FILM

• The blood typically shows reduced numbers of normal cells, with dysplastic changes in all myeloid lineages, and circulating blasts.

• The bone marrow aspirate and trephine show dysplasia, increased blasts, abnormal megakaryocytes and variable myelofibrosis

• Morphology- Usually M7

• Occasionally, other FAB types (M0, M1 and M2)

CD 41 +ve blasts

by APAAP

Acute Megakaryoblastic Leukemia: AML-M7

Treatment of ML-DS

• The basis of the favourable response is primarily increased sensitivity of the ML-DS blasts to cytarabine

• Contemporary regimens produce 5-year survival rates of 80%

• The main reason for treatment failure is toxicity (resistant disease and relapse are rare), predominantly due to mucositis and infection.

• Thus, current studies aim to reduce treatment intensity when compared with children with acute myeloid leukaemia who do not have Down syndrome

DS-AMKL v/s non-DS AMKL

• DS children have a 500-fold increased risk of developing AMKL

• DS AMKL -narrow temporal window before 4 years of age• In some, but not all cases of DS-AMKL, there is documented

evidence of previous TMD, and the megakaryoblasts in AMKL and TMD are morphologically, immunophenotypically, and ultrastructurally similar

• DS -AMKL has an unusually good prognosis• TMD and AMKL show a distinct pathogenetic basis

GATA1

• GATA1 is a DNA-binding transcription factor encoded on the X-chromosome (Xp11.23)

• Key regulator of megakaryocyte, erythroid, eosinophil, and mast cell differentiation

• Acquired somatic mutations in one copy of GATA1 were demonstrated both in TMD and in DS AMKL.

• These mutations disappeared with resolution or remission of disease

GATA1

• N-terminal truncation of GATA1 could confer a selective advantage for proliferation of hematopoietic cells

• Altered expression of any number of chromosome 21 genes

• One of these includes RUNX-1, a key hematopoietic gene

often deregulated in leukemogenesis.

Why does the TMD clone extinguish

• Though GATA1 mutation provides a proliferative advantage, it fails to immortalize the clone

• Results in a self-limiting illness

Model of the relationship betweenGATA1 mutations and TMD and AMKL in DS

LINK BETWEEN TAM AND ML-DS

• TAM and ML-DS blast cells have near identical morphology, immunophenotype and ultrastructure.

• GATA-1 mutation is distinct for TAM and ML-DS, but not other Down syndrome and non-Down syndrome leukaemias

TAM and ML-DS: a multi-step model of leukemogenesis

• First, a fetal haemopoietic cell has to be trisomic for chromosome 21.

• The second required event is acquisition of a GATA1 mutation that results in production of a N-terminal truncated GATA1 protein

• As GATA1 is encoded on the X-chromosome, in both males and females (due to X inactivation) only the mutant N-terminal GATA1 is expressed

• It is likely that GATA1s is a weak oncogene that fails to control excessive megakaryocyte differentiation

TAM and ML-DS: a multi-step model of leukemogenesis

• As not all cases of TAM progress to ML-DS, additional, genetic or epigenetic events are required for progression to ML-DS

• Presumably, in cases where these mutations are not acquired the TAM clone extinguishes

ALL-DS

• ALL-DS is 1.7 times more frequent than ML-DS

• clinical features of acute lymphoblastic leukaemia are similar in children with or without Down syndrome

• Most children (>90%) have a precursor B-cell immunophenotype (CD79a+,CD10+, CD19+)

• In Down syndrome, ALL is more likely to have an adverse (hypodiploidy) rather than favourable prognostic karyotype (high hyperdiploidy and t(12:21))

Type of leukemia Genetic abnormality Reported number of cases

DS-ALL : Chromosomal:

Intragenic:

- t(12;21)(p13;q22)- t(8;14)(q11;q32)- del(9p)- add(X)

-JAK2 (ΔIREED, R683S,R683G, R683K)-PTPN11 (E76K)-RAS (G12D)

17/3224/20915/18680/238

28/130

1/101/10

TMD Intragenic: -GATA1-JAK3-TP53

73/755/401/13

DS-AMKL Chromosomal:

Intragenic:

-Trisomy 8-Monosomy 7/completeor partial del(7q)

-GATA1-JAK3-FLT3-TP53-JAK2

6/347/34

58/657/532/356/282/32

Pediatric MDS

Disease Blood findings Bone marrow findingsRefractory cytopenia with unilineage dysplasia (RCUD)

-Refractory anemia (RA)-Refractory neutropenia (RN)-Refractory thrombocytopenia (RT)

- Unicytopenia or bicytopenia1

- No or rare blasts2

- Unilineage dysplasia: > 10% of the cells in one myeloid lineage

- < 5% blasts- < 15% erythroid precursors are ring

sideroblastsRefractory cytopenia with ring sideroblasts (RARS)

- Anaemia- No blasts

- > 15% erythroid precursors are ring sideroblasts

- Erythroid dysplasia only- < 5% blasts

Refractory cytopenia with multilineage dysplasia (RCMD)

- Cytopenia(s)- No or rare blasts (<1%)2

- No Auer rods- <1 x 109/L monocytes

- Dysplasia in >10% of the cells in > two myeloid lineages

- < 5% blasts- No Auer rods- + 15% ring sideroblasts

Refractory anaemia with excess blasts-1 (RAEB-1)

- Cytopenia(s)- < 5% blasts2

- No Auer rods- <1 x 109/L monocytes

- Unilineage or multilineage dysplasia - 5-9% blasts2

- No Auer rods

Refractory anaemia with excess blasts-2 (RAEB-2)

- Cytopenia(s)- 5-19% blasts2

- Auer rods + 3

- <1 x 109/L monocytes

- Unilineage or multilineage dysplasia - 10-19% blasts2

- Auer rods + 3

Myelodysplastic syndrome with isolated del(5q)

- Anaemia- Usually normal or

increased platelet count- No or rare blasts (<1%)

- Normal to increased megakaryocytes with hypolobated nuclei

- < 5% blasts- Isolated del(5q) cytogenetic abnormality- No Auer rods

Myelodysplastic syndrome- unclassifiable (MDS-U)

- Cytopenias- < 1% blasts2

- Unequivocal dysplasia in less than 10% cells in one or more myeloid cell lines when accompanied by a cytogenetic abnormality considered as presumptive evidence for diagnosis of MDS

- < 5% blastsChildhood myelodysplastic syndromeProvisional entity: Refractory cytopenia of childhood (RCC)

- Cytopenias- < 2% blasts

- Unilineage or multilineage dysplasia - <5% blasts

Pediatric MDSClassification• Refracory cytopenia of childhoodRCC (peripheral blood [PB] blasts

2% and BM blasts 5%),

• Refractory anemia with excess blasts (RAEB; PB blasts 2%-19% and/or BM blasts 5%-19%) and

• RAEB in transformation (RAEB-T; PB and/or BM blasts 20%-29%)

• Secondary MDS:after prior chemotherapy or radiation therapy, after prior acquired aplastic anemia, or in IBMF disorders and familial diseases.

Classification of Childhood Aplastic Anemia and Myelodysplastic Syndrome. Charlotte M. Niemeyer and Irith Baumann. American society of hematology

EPIDEMIOLOGY

12-20% of children with MDS progress to AML

Account for 1 to 5.5% of all pediatric hematological malignancies (Indian Pediatrics 2001; 38)

Near-equal sex distribution; median survival < 12 months

The median age is 5-8 yrs (avg. 6.8 yrs)

Most long-term complications are related to myeloablative therapy with stem cell rescue. Sequelae include short stature, obesity, gonadal failure, hypothyroidism, and cataracts.

Refractory Cytopenia of Childhood(RCC)

Persistent cytopenia <5% blasts in Marrow <2% blasts in periphery Cytological dysplasia

Etiology- unknown50% of all MDSM=FDown’s syndrome excluded75% have hypocellularityTrephine is indispensable

Difficult D/D:Hypocellular RCC vs aplastic anemia / inherited BM failure disorders

Presentation

Median age: 6 yrs. Asymptomatic-20% Malaise, Pallor(Hb < 10g/dL)-50% Bleeding(thrombocytopenia <150X 109/L) Fever Infections/ severe neutropenia-25% Lymphadenopathy No/minimal hepatosplenomegaly Macrocytosis Dysplasia present ≥ 2 / > 10% single lineage

Minimal diagnostic criteria for RCCErythropoiesis Granulopoiesis Megakaryopoiesis

PB Dysplastic changes in at least 10% neutrophils<2% blasts

BMA Dysplastic/megaloblastoid changes at least 10% precursors

Dysplasia at least 10% precursors<5% blasts

UnequivocalMicromegakaryocytesOther dysplastic changes in variable no.

Trephine

A few clusters of at least 20 erythroid precursorsStop in maturation with increased no. of proerythroblastsIncreased no. of mitoses

No minimal diagnostic criteria

UnequivocalMicromegakaryocytesIHC is obligatory (CD61, CD41)Other dysplastic changes in variable no.

Periphery Marrow

Ovalomacrocytes Megaloblastoid erythropoiesis

Elliptocytes Nuclear budding

Acanthocytes Ringed sideroblasts

Stomatocytes Internuclear bridging

Teardrops Karyorrhexis

Nucleated erythrocytes Nuclear fragments

Basophilic stippling Cytoplasmic vacuolization

Howell-Jolly bodies Multinucleation

ErythroidErythroid

-

Myeloid

Periphery Marrow

Pseudo-Pelger-Hue't anomaly Defective granulation

Auer rods Maturation arrest at myelocyte stage

Hypogranulation Increase in monocytoid forms

Nuclear sticksHypersegmentationRing-shaped nuclei

Abnormal localization of immature precursors

Megakaryocytic

BM: RCC, showing an aggregate of dysplastic megakaryocytes.

RAEB-T, increased numbers of blasts forming a small cluster (centre) : an abnormal localization of immature precursors or ALIP

Cytogenetics

• Monosomy 7 is the most common cytogenetic abnormality in childhood MDS (30%)

• Trisomy 8 and trisomy 21 are the second most common numerical abnormalities.

Unbalanced +8-7 or del(7q)-5 or del(5q)del(20q)-Yi(17q) or t(17p)-13 or del(13q)del(11q)del(12p) or t(12p)del(9q)idic(X)(q13)

Balanced t(11;16)(q23;p13.3)t(3;21)(q26.2;q22.1)t(1;3)(p36.3;q21.2)t(2;11)(p21;q23)inv(3)(q21q26.2)t(6;9)(p23;q34)

Recurring chromosomal abnormalities seen in MDS

D/D of MDS:Need ≥1 Marrow Finding & CG

• D/D : Is that of anemia, thrombocytopenia, and/or leukopenia.

Elimination of known etiologies of cytopenias, along with a dysplastic

bone marrow, is required to diagnose a myelodysplastic syndrome.

• Other anemias: megaloblastic

CDA

B12, folate/vitamin E deficiencies

sideroblastic anemia

• Leukemia/pre-leukemia:Megakaryocytic leuk.

Myelofibrosis

PNH

• Toxins: Arsenic, chemotherapy

• Virus: HIV

• Other causes of cytopenias -lupus, hepatitis, renal failure or heart failure,

hemolytic anemia, monoclonal gammopathy. Age-appropriate cancers

D/D

Infections: CMV, Herpes, Parvo B19, visceral leishmaniasis

Vitamin deficiency: B12, folate, E

Metabolic disorders: mevalonate kinase def.

Rheumatic diseases

Mitochondrial deletions: Pearson’s syndrome

Inherited bone marrow failure disorders: fanconi,

dyskeratosis congenita,

Acquired aplastic anemia during hematological recovery

Etiology

80% primary. 40% which have an abnormal karyotype

20% secondary. Secondary causes include:

1. Neurofibromatosis type 1 (NF1): JMML;200-500-fold increased risk.

2. Shwachman-Diamond syndrome is c/b pancreatic insufficiency with neutropenia. MDS:10-25%

3. Fanconi anemia (4-7%): 48% of patients with FA develop leukemia or MDS by 40 years. It is often a/w monosomy 7 & duplication of 1q. Diagnosing refractory cytopenia in FA difficult.

4. Familial leukemia (2-6%) /familial marrow failure: JMML, in families with monosomy.

5. Noonan’s syndrome: germline mutation of PTPN 11 (protein tyrosine phosphatase SHP2) or K-RAS-35%

SECONDARY CAUSES, Cont…

6. Kostmann syndrome (0.6%) is congenital agranulocytosis. Survival significantly improved with (G-CSF).

7. Congenital amegakaryocytic thrombocytopenia

8. Diamond-Blackfan anemia, Bloom syndrome, Dubowitz syndrome, & Seckel syndrome

9. Alkylating agents (2-5%) is a/w monosomy 7 & chrom 5 del. Poor response rates. Epipodophyllotoxins is a/w MDS 1 to 3 yrs after exposure & often involves rearrangements of the MLL gene, whereas MDS after therapy with alkylators develops later & involves del chrom 5 or 7.

10. Topoisomerase inhibitor rarely. Patients usually develop AML.

11. MDS develops in 10-15% of patients with acquired aplastic anemia who are not treated with stem cell transplant

12. Gain of 1q (Leukemia Research Volume 30, Issue 11, 1437-1441)

Mutations in the telomerase component TERC, which are observed in

patients with dyskeratosis congenita, are occasionally seen in pediatric

myelodysplasia syndrome without the typical phenotypic features

The biologic mechanisms implicated in the pathophysiology of myelodysplasia

syndrome to date include:

1.genomic instability,

2.epigenetic changes: Methylation silencing of p15

3.abnormal apoptosis machinery,

4.abnormal signal-transduction pathways

5.immune dysregulation (production of inhibitory cytokines/ T-cell

mediated suppression

6.the role of the bone marrow microenvironment & stromal defect.

7.Clonal disorders

8.Genetic polymorphism - GST-theta1 null genotype

Sharon M Castellino, et al, e-medicine, April, 2008

Molecular Genetics of MDS• AML1/RUNX1 gene: point mutations –may be a useful to differentiates

radio-induced MDS/AML from spontaneous MDS/AML( Radiation

Research; 49, 5:2008)

Gene amplification (c-myc) & overexpression of MDR-1 ( accumulation of

P-170 leading to resistance to chemo)

• Chromosome 7 & 20 abnormalities in Shwachman synd: “mutator

phenotype”

• CALCA / CDKN2B are frequently methylated in pediatric MDS. It suggests

that aberrant methylation in pediatric MDS seems to be similar to adult

MDS, thus pediatric patients could be also benefited with treatment

using demethylating agents.

VIDAL Daniel O et al, Leukemia research, 2007

FPC Prognostic Scoring System for Pediatric MDS

At diagnosis

Platelet < 40 x 109 – Score 1Cytogenetic complexity- Score 2HbF >10%- Score 1

(2/more clonal structural/numerical abnormalities)Score 0 having a 5-year survival of 61.6% vs score of 2/3 all died < 4 yrs of dx.

Passmore et a a study of 68 children , BLOOD

The (IPSS) for MDS in adults seems to have limited prognostic impact in children ...Leukemia (2003) 17, 277–282

Thank you