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Hematopathology WHO MPN, Mastocytosis, MPN/MDS, & MDS > Specific MDS Categories > Flashcards

Specific MDS Categories Flashcards

1
Q

What is the definition of MDS

with single lineage dysplasia ?

A
  • single lineage dysplasia (>10% of dysplastic cells)
  • usually cytopenia (anemia) or bicytopenia
    • can have neutropenia with thrombocytopenia

Note: the lineage with dysplasia and which cytopenias are present should be identified in the report

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2
Q

How should cases with unknown SF3B1 mutation status and

5-14% RS be classified and single lineage dysplasia ?

A
  • MDS with single lineage dysplasia
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3
Q

In what situation would a patient be observed

for 6 months prior to rendering a diagnosis

of MDS-SLD ?

A
  • if there is SLD and cytopenias but NO clonal abnormality

IMP: all non-clonal causes must first be excluded prior to rendering this diagnosis.

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4
Q

Which supplement has been implicated

with severe cytopenias and dysplastic changes ?

A
  • Zinc supplementation
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5
Q

What essentially excludes the diagnosis

of MDS-SLD?

A
  • presence of peripheral blood blasts
    • occasionally rare blasts may be seen (<1%)
  • If
    • 1% blasts on peripheral blood on 2 successive occasions
    • <5% blasts in the bone marrow
    • this should be diagnosed as MDS-U due to the more aggressive clinical course
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6
Q

What entities should be investigated for

persistent neutropenia or thrombocytopenia ?

A
  • these are significantly less common than anemia in the general population
  • exclude:
    • Familial occurrence
    • comorbid conditions like immune disorders, T-LGL leukemia
    • viral infection
    • medications
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7
Q

What is the epidemiology of

MDS-SLD ?

A
  • accounts for up to 20% of cases
  • generally older adults with no sex predilection
  • generally present with symptoms of the cytopenia they have
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8
Q

Review microscopic section pg. 108-109.

A
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9
Q

What cytogenetic abnormalities

have been more frequently described in

MDS-SLD ?

A
  • del 20q
  • gain of chromosome 8
  • abnormalities in chromosome 5 and 7
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10
Q

What 2 genes tend to be

mutated in MDS-SLD ?

A
  • most commonly mutated (but not specific)
    • TET2
    • ASXL1

IMP: SF3B1 mutation is rare

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11
Q

What is the prognosis of patients

with MDS-SLD ?

A
  • median survival is ~66 months
  • rate of progression to AML at 5 years - 10%
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12
Q

What is the definition of MDS-RS ?

A
  • cytopenias, morphologic dysplasia and RS >15%
    • or SF3B1 mutation and >5% RS
  • BM blasts < 5%, PB blasts <1%, NO Auer rods
  • Two Categories
    • MDS-RS SLD:
      • anemia and erythroid dysplasia
    • MDS-RS MLD:
      • any cytopenias and dysplasia in 2-3 lineages
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13
Q

What is the epidemiology of

MDS-RS ?

A
  • MDS-RS SLD: 11% of MDS cases
  • MDS-RS MLD: 13% of MDS cases
  • older age group with similar frequency in M:F

Note: the liver and spleen may show evidence of iron overload

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14
Q

What is a ring sideroblast?

A
  • erythroid precursor with abnormal accumulation of iron in the mitochondria
    • some iron deposited as mitochondrial ferritin
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15
Q

Read microscopic findings pg. 109-110.

A
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16
Q

What are other causes of

ring sideroblasts ?

A
  • alcohol
  • toxins ( lead and benzene)
  • drugs (isonizid)
  • copper deficiency (which may be induced by zinc toxicity)
  • congenital sideroblastic anemia
    • tends to present at a much younger age
    • patients have a microcytic anemia
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17
Q

Read genetic profile of MDS-RS p. 110.

A
18
Q

What are the prognostic and predictive factors

for MDS-RS ?

A
  • SLD: 1-2% of cases progress to AML
    • OS: 69-108 months
  • MLD: 8% progress to AML
    • OS 28 months

IMP: in SF3B1 mutants MDS-RS cases, RUNX1 mutation associated with shorter survival.

19
Q

What is the definition of MDS-MLD ?

A
  • one or more cytopenias and dysplastic changes in 2 or more myeloid lineages
  • BM blasts: <5%
  • PB blasts: <1%
  • No auer rods
  • monocytes are < 1x10^9/L
20
Q

What is the definition of

a micromegakaryocyte?

A
  • they are the size of a promyelocyte or smaller
  • non-lobated or bilobated nucleus
21
Q

For classification purposes in MDS,

how should the % of blasts be determined ?

A
  • based on microscopic differential on the aspirate smear
  • should not be done based on the flow cytometry %
22
Q

What is the prognosis for

patients with MDS-MLD?

A
  • have similar mutation profiles to those with excess blasts and AML by whole genome sequencing.
  • prognosis relates to karyotype and other mutations as well as blast % and dysplasia
  • evolve to AML 15-28% at 2 and 5 years respectively
  • median overall survival is 36 months
23
Q

What is the definition of MDS-EB ?

A

in general:

  • 5-19% blasts in BM
  • 2-19% blasts in PB
  • overall must be < 20% blasts
  • Have EB-1 and EB-2
    • EB-1
      • 5-9% blasts in BM
      • 2-4% blasts in PB
      • No Auer rods
    • EB-2
      • Auer rods or
      • 10-19% blasts in BM
      • 5-19% blasts PB
24
Q

What is the epidemiology of

MDS-EB ?

A
  • accounts for ~40% of all MDS
  • >50 year old patient
  • etiology is unknown but exposures have been implicated:
    • environmental toxins
    • pesticides
    • petroleum derivatives
    • heave metals
    • cigarette smoke
25
Q

Review the microscopic findings

for MDS-EB on pg. 113-114.

A
26
Q

The presence of what genetic findings

is associated with a poor prognosis

in MDS-EB ?

A
  • high-risk (complex karyotype)
  • mutations in :
    • TP53
    • RUNX1
    • ASXL1
27
Q

What entity can MDS-EB with myelofibrosis

overlap with clinically and morphologically ?

A
  • Acute panmyelosis and fibrosis
  • abruspt onset of fever and bone pain
  • along with higher blast counts
28
Q

Expression of what immunophenotypic

marker has been associated with

worse prognosis in MDS-EB ?

A
  • CD7
29
Q

How often do FLT3 and NPM1 occur

in MDS-EB?

A
  • These are rare in MDS-EB but common in AML
  • IF they are present these patients progress more quickly to AML
30
Q

What is the prognosis of

MDS-EB ?

A
  • tend to have progressive bone marrow failure with increased cytopenias
  • 25-33% progress to AML (EB-1 and EB-2 respectively
  • median survival: 16 months and 9 months respectively
31
Q

What is the definition of

MDS with isolated del 5q ?

A
  • anemia (with or without other cytopenias)
  • may have thrombocytosis
  • cytogenetics:
    • del 5q
    • may have another abnormality except for monosomy 7 or del 7q
  • PB blasts <1%
  • BM blasts <5%
  • Auer rods are absent
32
Q

What is the epidemiology and etiology

of MDS with del 5q ?

A
  • occurs more often in women, median age 65
  • etiology is a presumed loss of tumor suppressor genes or genes in the minimally deleted region of 5q33.1

Note: haploinsufficiency of additional genes on 5q (APC [another WNT pathway regulator] and EGR1) may also contribute to disease pathogenesis.

33
Q

What are the clinical features of MDS del 5q ?

A
  • often a severe, macrocytic anemia
  • thrombocytosis is present in 1/3-1/2 of cases
    • note: thrombocytopenia is uncommon
  • pancytoepenia is rare
    • IMP: if there is a del 5q but the patient has pancytopenia it is essential to classify this as MDS-U because the clinical behavior is uncertain.
34
Q

What are the key microscopic findings of MDS del 5q ?

A
  • erythroid hypoplasia is usually seen
    • dysplasia in erythroid is less pronounced
  • megakaryocytes
    • increased to normal in number
    • normal to slightly decreased in size
    • non-lobated to hypolobated nuclei
  • significant granulocytic dysplasia is not seen
  • Ring sideroblasts can be present and do not exclude the diagnosis if all other features are identified
35
Q

What is the cell of origin

in MDS del 5q ?

A
  • hematopoietic stem cell
    • FISH for del 5q shows the abnormality in differentiating erythroid, myeloid and megakaryocytic cells
    • generally not seen in mature lymphoid cells
36
Q

What are the genetics of MDS del 5q ?

A
  • defining abnormality: interstitial deletion of chromosome 5
    • size of the deletion and the breakpoints vary
    • bands q31-q33 are invariably deleted
  • another abnormality may be present with the exception of monosomy 7 or del 7q
  • Note:
    • a small subset of patients also show concomitant JAK2 V617F and MPL mutations
37
Q

What are the prognostic and predictive factors

of MDS del5q ?

A
  • 66-145 months with transformation to AML occurring in <10% of cases
    • good prognosis
  • significant granulocytic dypslasia has been associated with additional cytogenetic abnormalities and an inferior outcome
38
Q

What is the available treatment for

MDS del 5q ?

A
  • Lenalidomide (thalidomide analogue)
    • promotes ubiquitin mediated degradation
39
Q

What mutation should be evaluated for in MDS del 5q

and why is it important ?

A
  • TP53 mutation
    • present in a significant subset of cases and is associated with an increased risk of leukemic transformation
    • predicts inferior response to lenalidomide
    • predicts shorter survival
  • recommended that TP53 be evaluated in every case of del 5q
40
Q

What is the definition of MDS-U ?

A
  • category of MDS that initially lack appropriate findings for classification into any other MDS category.
41
Q

Read p. 116

A

Hematopathology WHO MPN, Mastocytosis, MPN/MDS, & MDS (17 decks)

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