Myelodysplastic Syndromes

Primary Author South, Sarah T., PhD.

Key Points

Molecular Testing for Myelodysplastic Syndrome (MDS)

Genetic studies are required at the time of diagnosis of MDS not only for identifying specific genetic abnormalities but also for monitoring disease progression. Unfortunately, more than half of patients with MDS have a normal karyotype, making disease-monitoring difficult.

Patients with a normal karyotype but aggressive disease may have abnormalities that cannot be identified by FISH or conventional cytogenetics. Cytogenomic SNP microarray is the test of choice for these patients. Cytogenomic SNP microarray can detect both copy-number variation (loss or gain of DNA) and loss of heterozygosity (LOH), which is often due to mutations and subsequent selection of mutant tumor-suppressor genes and oncogenes. In addition, cytogenetically-identified abnormalities may be monitored by FISH.

  • Conventional cytogenetics, FISH, and cytogenomic SNP microarray comparisons (see table below)
CONVENTIONAL CYTOGENETICSFLUORESCENCE IN SITU HYBRIDIZATION (FISH)CYTOGENOMIC SNP MICROARRAY
SUGGESTED USE
Diagnosis, prognosis, and monitoring of MDS

When combined with conventional cytogenetics, diagnostic accuracy may be improved

FISH is more sensitive than conventional cytogenetic analysis for detection of clonal abnormalities

Preferred test for MDS patients with a normal karyotype

Detects prognostically important genomic aberrations (loss/gain of DNA and/or loss of heterozygosity)

LIMITATIONS

Cannot be used to monitor MDS in patient with normal karyotype; more than half of MDS patients have normal karyotype

Cannot be used to monitor MDS unless a previous abnormality by FISH has been identified; more than half of MDS patients have normal karyotype

Technique will detect only copy-number imbalances and LOH in the nuclear genome

Does not detect balanced rearrangements such as translocations, inversions, and balanced insertions

May not detect low-level mosaicism (<15-20%)

Does not detect low-level clones – not recommended for minimal residual disease (MRD)

COMMENTS

Cannot detect copy-neutral loss of heterozygosity (LOH) events that are associated with hematologic malignancies

Success rate dependent upon growth of tumor cells in culture

Often cannot unravel the specific anatomy of marker chromosomes that involve multiple rearrangements; cryptic mutations can be missed or misidentified

Cannot detect copy-neutral loss of heterozygosity (LOH) events that are associated with hematologic malignancies

Can examine only a few loci at a time; limited to the specific chromosomal regions to which the respective probes bind

Mutations involving any other chromosome or other regions on the same chromosome are not identified

Complements the established genetic methods and leads to a comprehensive genetic characterization of MDS

More sensitive in the detection of both common karyotype abnormalities as well as more subtle genomic changes not detected by FISH or cytogenetics (ie, genetic abnormalities that have been shown to be associated with poor prognosis in myeloid malignancies)

Detects MDS-associated unbalanced abnormalities and LOH in MDS patients with normal karyotype (eg, uniparental disomies like UPD7q, UPD11q and UPD17p)

ARUP TESTS
Chromosome Analysis, Bone Marrow with Reflex to Genomic Microarray 2007130

Myelodysplastic Syndrome (MDS) Panel by FISH 2002709

Acute Myelogenous Leukemia (AML) with Myelodysplastic Syndrome (MDS), or Therapy-Related AML, by FISH 2002653

Cytogenomic SNP Microarray-Oncology  2006325

 Cazzala M et al 2011; Shih AH 2011; Simons A 2012;  Tiu RV 2011

Diagnosis

Indications for Testing

  • Abnormal CBC or peripheral smear without other obvious etiology – may see macrocytic anemia, other cytopenias, dysplastic cells in peripheral smear

Criteria for Diagnosis

  • MDS – International Consensus Working Group (2007) recommendations
    • Stable cytopenia for >6 months
      • Only 2 months required if accompanied by specific karyotype or bilineage dysplasia
    • Exclusion of other potential disorders as a primary reason for dysplasia or cytopenia
    • At least one MDS-related (decisive) criterion
      • Unequivocal dysplasia (≥10% in ≥1 of the 3 major bone marrow lineages)
      • Blast cell count of 5-19%
      • Specific MDS-associated karyotype [eg, del(5q), del(20q), +8, -7/del(7q)]
    • Co-criteria help confirm the diagnosis
      • Bone marrow histology and immunohistochemistry to detect fibrosis, dysplastic megakaryocytes, atypical localization of immature progenitors
      • Flow cytometric analysis to identify abnormal myeloid antigen patterns, abnormal CD34 expression in blasts
      • Molecular markers to detect myeloid clonality
  • Presumptive MDS - this diagnosis is allowed in individuals with refractory cytopenia(s) who lack unequivocal dysplasia if specific cytogenetic abnormalities are detected
  • AML with myelodysplasia-related changes
    • >20% blood or marrow blasts AND previous history of MDS or MDS-related cytogenetic abnormality OR multilineage dysplasia
      • Dysplasia in at least 50% of cells in 2 or more hematopoietic lineages
    • Absence of cytogenetic abnormalities described in AML with recurrent genetic abnormalities
    • No history of prior cytotoxic therapy for an unrelated disease
  • Therapy-related myeloid neoplasms (t-MDS, t-MDS/MPN, or t-AML)
    • Myeloid neoplasms (excluding MPNs) that arise as a consequence of cytotoxic or radiation therapy
    • May be subdivided by blast count but behave as a single biologic disease

Histology

  • Classification based on bone marrow histology, immunohistochemical features, flow cytometry and cytogenetic FISH findings
    • Bone marrow biopsy – diagnosis almost exclusively made using marrow appearance
      • Criteria – dysplasia in ≥10% of myeloid lineage cells
    • Cytogenetic testing for recurrent chromosome abnormalities consistent with MDS
      • FISH – does not add substantially for diagnosis in cytogenetically normal cases
      • Microarray – identification of MDS-associated imbalances and loss of heterozygosity in ~20% of cases with normal cytogenetic chromosome analysis
      • Most common abnormalities – del(5q) and del(7q), trisomy 8
  • Refer to Key Points tab for comparisons of FISH, conventional cytogenetics, and cytogenetics SNP microarray for diagnosis
  • Other modalities in difficult-to-diagnose cases
    • Flow cytometry
      • Changes not specific for MDS; may be most useful in ruling out other neoplasms in patient with cytopenias
      • Absence of  flow cytometric abnormalities does not exclude MDS
    • Immunohistochemistry – CD117 (c-Kit); CD34 (QBEnd/10); myeloperoxidase (MPO) to identify abnormal localization of immature precursors and increased blasts

Prognosis

  • Most accurately defined by cytogenetic testing, FISH, and cytogenetic SNP microarray (see Key Points tab)
  • Dependent on karyotype, % blasts, and number of cytopenias present
  • MDS International Prognostic Scoring System (IPSS)

    IPSS-R Scoring System (2012)

    Prognostic subgroup

    Cytogenetic Abnormality

    Single

    Double

    Complex

    Very Good

    del(11q); -Y

    ------------

    ------------

    Good

    Normal; del(5q); del(12p); del(20q)

    del(5q) combined with another abnormality

    ------------

    Intermediate

    del(7q); +8; i(17q); +19; +21; any other independent clones

    Any other abnormality in combination

    ------------

    Poor

    inv(3)/t(3q)/del(3q); -7

    -7/del(7q) combined with another abnormality

    3 abnormalities

    Very Poor

    ------------

    ------------

    >3 abnormalities

    Greenberg PL, 2012
  • Newest prognostication from WHO classification-based scoring system incorporates transfusion burden
    • Poor prognosis with refractory anemia with excess blasts (RAEB) or refractory anemia with excess blasts in transformation (RAEB-t)
      • Median survival 5-12 months
      • Disease transforms to AML in 40-50%
    • Better prognosis with refractory anemia (RA) or refractory anemia with ring sideroblasts (RARS)
      • Median survival 3-6 years
      • Disease transforms to AML in 5-15%

Differential Diagnosis

Clinical Background

Myelodysplastic syndromes (MDS) are clonal hematopoietic malignancies characterized by ineffective hematopoiesis, cytopenia, unilineage, or multilineage dysplasia, and a susceptibility to leukemia, especially AML.

Epidemiology

  • Incidence  
    • 5/100,000 in the general population
    • 22-45/100,000 in the elderly population (>70 years)
  • Age – median is 65-70
  • Sex – M>F

Classification

  • World Health Organization (WHO) classification of MDS
    MDS Subtype2008 WHO Classification
    BloodBone Marrow

    Refractory cytopenias with unilineage dysplasia (RCUD)

    • Refractory anemia (RA)
    • Refractory neutropenia (RN)
    • Refractory thrombocytopenia (RT)
    • Unicytopenia or bicytopenia1
    • No or rare blasts (<1%)2
    • Unilineage dysplasia ≥10% of one cell line
    • <5% blasts
    • <15% of erythroid precursors are ring sideroblasts
    Refractory anemia with ring sideroblasts (RARS)
    • ≥15% erythroid precursors are ring sideroblasts
    • Erythroid dysplasia only
    •  <5% blasts
    Refractory cytopenia with multilineage dysplasia (RCMD)
    • Cytopenia(s)
    • No or rare blasts (<1%)
    • No Auer rods
    • <1x109/L monocytes
    • Dysplasia in ≥10% of cells in ≥2 myeloid lineages
    •  ±15% ring sideroblasts
    • <5% blasts
    • No Auer rods
    Refractory anemia with excess blasts-1 (RAEB-1)
    • Cytopenia(s)
    • <5% blasts
    • No Auer rods
    • <1x109/L monocytes
    • Unilineage or multilineage dysplasia
    • No Auer rods
    • 5-9% blasts
    Refractory anemia with excess blasts-2 (RAEB-2)
    • Cytopenia(s)
    • 5-19% blasts
    • Auer rods
    • <1x109/L monocytes
    • Unilineage or multilineage dysplasia
    • Auer rods ±
    • 10-19% blasts
    Refractory anemia with excess blasts in transformation (RAEB-t)Subtype not used
    Myelodysplastic syndrome, unclassified (MDS-U)
    • Cytopenias
    • ≤1% blasts
    • Unequivocal dysplasia in <10% of cells in ≥1 myeloid cell lines when accompanied by a cytogenetic abnormality considered as presumptive evidence for a diagnosis of MDS
    •  <5% blasts
    MDS associated with isolated del(5q)
    • Anemia
    • Platelets normal or increased
    • No or rare blasts (<1%)
    • Normal to increased megakaryocytes with hypolobated nuclei
    • Isolated del(5q)
    • <5% blasts
    • No Auer rods
    Chronic myelomonocytic leukemia (>1,000 monocytes/µL blood)

    Subtype not used

    1Bicytopenia may occasionally be observed; cases with pancytopenia = MDS-U

    2If marrow myeloblasts <5% but 2-4% myeloblasts in blood = RAEB-1

    3Auer rods and <5% myeloblasts in blood and <10% in marrow = RAEB-2

    Note: NCCN endorses using both the French-American-British (FAB) and WHO classification criteria for RAEB-t patients 

Risk Factors

  • Increased age
  • Occupational exposures
    • Benzene-containing products
    • Pesticides
    • Organic solvents
    • Heavy metals (lead, arsenic)
  • Drug exposures
    • Alkylating agents, other cytotoxic agents
    • Azathioprine
    • Mycophenolate
  • Therapy-related – 10-15% of MDS occurs following chemotherapy and radiation treatment
  • Genetic

Pathophysiology

  • Clonal expansion of the multipotential hematopoietic cell
  • Primary mechanism is defective maturation of marrow cells coupled with premature cell death

Clinical Presentation

  • MDS
    • May be asymptomatic
      • Disease is generally indolent, with blood counts remaining relatively stable over several months or longer
    • Most common symptoms
      • Anemia – pallor, weakness, exertional dyspnea
      • Increased infection from neutropenia
      • Bleeding/bruising from thrombocytopenia
    • Complications
      • 25-30% progress to AML; incidence depends on MDS subtype
        • Lower response rate to standard therapy for patients >65 years with de novo AML
      • Death from complications of cytopenia (neutropenia in particular)
  • AML with myelodysplasia-related change
    • Elderly individuals predominate
    • Represents 25-30% of AML cases
    • Generally presents with pancytopenia
    • Chromosome abnormalities are similar to those found in MDS unrelated to cytotoxic agents
      • Often involve gain or loss of major segments of specific chromosomes with complex karyotypes
  • Treatment-related myeloid neoplasms
    • Late complication of cytotoxic or radiation therapy
      • Rate of development does not differ between those with a hematologic versus solid malignancy
    • Accounts for 10-20% of all AML, MDS, and MDS/myeloproliferative neoplasms (MPN)
    • 90% have clonal chromosomal abnormality
      • Often complex
      • Similar to those observed in AML with myelodysplasia-related change
    • Disease differs based on type of therapy (alkylating agent/radiation versus topoisomerase II)
      • Individual may have received both therapies at some point during an illness, meaning either presentation can occur
    • t-MDS/t-AML arising after alkylating agent and/or radiation therapy
      • 80–85% of treatment-related myeloid neoplasms
      • Latency period 3-7 years (median 5 years)
      • Initial presentation – MDS with trilineage dysplasia
      • Cytogenetics (most common)
        • Abnormalities of chromosomes 5, 7, or complex karyotypes
    • t-AML/t-MDS arising after topoisomerase II inhibitor therapy
      • ~15% of treatment-related myeloid neoplasms
      • Latency period 2-3 years
      • Initial presentation – AML (typically no antecedent MDS)
      • Cytogenetics
        • Balanced translocations
        • MLL rearrangements
        • t(15;17)
        • inv (16)

Pediatrics

Clinical Background

Epidemiology

  • Incidence – 0.5-4/1,000,000 (rare)
  • Age – 6-8 years

Classification

  • Patients with 2-19% blasts in peripheral blood and/or 5-19% blasts in bone marrow may be classified using the adult schema provisional but exclude patients with Down syndrome
  • Additional pediatric entity of refractory cytopenia of childhood is recognized
    • <2% blasts in peripheral blood and <5% blasts in bone marrow
    • Bilineage dysplasia

Clinical Presentation

  • May be asymptomatic
  • Most common symptoms
    • Anemia – pallor, weakness, exertional dyspnea
    • Hepatomegaly/splenomegaly (5-10%)
    • Arthralgias

Diagnosis

  • Refer to Diagnosis and Key Points tabs

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Chromosome Analysis, Bone Marrow with Reflex to Genomic Microarray 2007130
Method: Giemsa Band/Genomic Microarray (Oligo-SNP array)

Diagnosis, prognosis,  and monitoring of MDS

Includes conventional cytogenetics with reflex to microarray if karyotype is normal

   
Chromosome FISH, Interphase 2002298
Method: Fluorescence in situ Hybridization

Use in conjunction with conventional cytogenetics for diagnosis, prognosis and monitoring of MRD in MDS therapy-related neoplasms

  • Specific FISH probes that must be requested with this test code and for this indication include -5/del(5q), -7/del(7q), +8, del20q,  MLL rearrangements (11q23), and EVI1 rearrangements (inv(3) or t(3q))

ARUP Oncology FISH Probes menu

Limit of detection is probe dependent; approximately 1-5% in interphase nuclei

 
Myelodysplastic Syndrome (MDS) Panel by FISH 2002709
Method: Fluorescence in situ Hybridization

Use in conjunction with conventional cytogenetics for diagnosis, prognosis, and monitoring of MRD in MDS

 Probes include

  • -5/del(5q)
  • -7/del(7q)
  • + 8
  • del(20q)

Each probe can be run as a part of the panel or individually

AML may also include abnormalities detectable by this panel

Chromosome alterations outside probe region are not detected  
Cytogenomic SNP Microarray - Oncology 2006325
Method: Genomic Microarray (Oligo-SNP Array)

Preferred test for MDS patients with normal karyotype to detect prognostically important genomic abnormalities

Useful in patients with <20 normal metaphases or with no mitosis to consider on conventional cytogenetics

Low-level mosaicism (<15-20%) may not be detected; test may not be appropriate for individuals with expected lower levels of malignant cells

Does not detect balanced rearrangements; FISH should be used to evaluate specific balanced rearrangements in the following

  • ALL – balanced translocation 9;22 (ABL1-BCR), translocation 12;21 (ETV6-RUNX1), and balanced rearrangement of MLL, IGH, MYC, and TCF3
  • AML – balanced translocation 15;17 (PML-RARA),  translocation 8;21 (RUNX1T1-RUNX1), and balanced rearrangement of the MLL or the CBFB gene

 Does not detect base pair mutations  and very small deletions/duplications; imbalances of the mitochondrial genome; low level clones (not recommended for MRD)

 
Acute Myelogenous Leukemia (AML) with Myelodysplastic Syndrome (MDS) or Therapy-Related AML, by FISH 2002653
Method: Fluorescence in situ Hybridization

Use in conjunction with conventional cytogenetics for diagnosis, prognosis, and monitoring of MRD in MDS

Probes include

  • -5/del(5q)
  • -7/del(7q)
  • 11q23 rearrangements
Chromosome alterations outside probe region are not detected  
CD117 (c-Kit) by Immunohistochemistry 2003806
Method: Immunohistochemistry

Aid in histologic diagnosis of myelodysplastic syndromes; identify abnormal localization of immature precursors and increased blasts

Stained and returned to client pathologist; consultation available if needed

   
CD34, QBEnd/10 by Immunohistochemistry 2003556
Method: Immunohistochemistry

Aid in histologic diagnosis of myelodysplastic syndromes; identify abnormal localization of immature precursors and increased blasts

Stained and returned to client pathologist; consultation available if needed

   
Myeloperoxidase (MPO) by Immunohistochemistry 2004014
Method: Immunohistochemistry

Aid in histologic diagnosis of myelodysplastic syndromes; identify abnormal localization of immature precursors and increased blasts

Stained and returned to client pathologist; consultation available if needed

   
Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Chromosome Analysis, Bone Marrow 2002292
Method: Giemsa Band

Diagnosis, prognosis, and monitoring of MRD in therapy-related MDS and/or AML

Chromosome Analysis, Leukemic Blood 2002290
Method: Giemsa Band

Identify recurrent chromosome abnormalities consistent with MDS

Leukemia/Lymphoma Phenotyping by Flow Cytometry 2008003
Method: Flow Cytometry

Aid in evaluation of hematopoietic neoplasms (ie, leukemia, lymphoma)

Monitor therapy in patients with established diagnosis of hematopoietic neoplasms

Specimens include peripheral blood, bone marrow, and tissue

Markers selected based on clinical history, previous flow studies, and pathologist interpretation

Available markers

Myelo/Mono: CD11b, CD13, CD14 (Mo2), CD14 (MY4), CD15, CD33, CD64, CD117, myeloperoxidase

T cell: CD1, CD2, CD3, CD4, CD5, CD7, CD8, TCR alpha-beta, TCR gamma-delta, cytoplasmic CD3

B cell: CD10, CD19, CD20, CD22, CD23, CD103, kappa, lambda, FMC7, cytoplasmic kappa, cytoplasmic lambda

Misc: CD11c, CD16, CD25, CD30, CD34, CD38, CD41, CD42b, CD45, CD56, CD57, CD61, HLA-DR, glycophorin, TdT, bcl-2, ALK-1, CD123, CD138, CD200, CD26, CD45