Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Flow Cytometry > ID of B lymphoblasts and B-ALL > Flashcards

ID of B lymphoblasts and B-ALL Flashcards

1
Q

How can B-ALL be identified by

flow cytometry ?

A
  • positive:
    • CD19, CD22, CD79a
    • HLA-DR, CD38, and CD10
    • TdT, CD34
  • negative:
    • surface light chain expression
    • negative or dim for CD45
  • SSC is low with minimally increased FSC (moderate)
  • Subset of B-ALLs are positive for:
    • CD13, CD33, CD71 and/or CD123
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the expression pattern of

B cell markers in B-ALL ?

A
  • moderate CD19
    • occasional cases have been reported with a reduced level
  • positive for CD79a and Pax-5
  • CD20
    • most often is negative but ~20% of cases can be partial, dim or variable

IMP:

  • NK cells can sometimes show non-specific B cell marker staining so must exclude if evaluating for MRD
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the pattern of expression of

CD34 and TdT in B-ALL ?

A
  • CD34 is usually positive but
    • ~30% of cases can be negative
    • lack of CD34 or partial expression is often seen in BCR-ABL1 B-ALL
  • TdT
    • is most often positive
  • ~4% of B-ALL
    • lack both TdT and CD34
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the pattern of expression of

CD71 and CD123 in B-ALL ?

A
  • CD71
    • positive on a subset (10-32%) of B-ALL
    • it is more often positive in T-ALL
  • CD123
    • is often positive
    • stronger expression is usually noted in B-ALL with mature phenotype
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the pattern of expression

of CD45 in B-ALL ?

A
  • may be completely negative but most cases show heterogeneous or variable expression
  • IMP
    • moderate expression can be occasionally seen
    • bright CD45 is never seen in B-ALL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the pattern of expression

for CD10 in B-ALL ?

A
  • majority of B-ALL show bright CD10 expression
    • BUT some cases may be CD10 negative
    • BCR-ABL1 associated B-ALL is bright for CD10
    • KMT2A associated B-ALL is negative for CD10
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the pattern of expression of

CD13, CD15, CD33, and CD65 in B-ALL ?

A
  • subsets of B-ALL may show myeloid marker expression
  • CD33 is more often positive than CD13
    • IMP: co-expression of both is RARE
  • Aberrant expression of CD13 or CD33 is more common in BCR-ABL1 positive B-ALL
  • KMT2A B-ALL
    • shows aberrant expression of CD15, CD33 and or CD65
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the immunophenotypic categories

often seen with B-ALL ?

A
  • Pro-B-ALL
  • Common ALL
  • Pre-B-ALL
  • Mature B-ALL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the immunophenotype of

pro-B-ALL and Common ALL ?

A
  • Pro-B-ALL
    • aka early pre-B-ALL
    • TdT+, CD19+, CD10-
  • Common ALL
    • CD10+
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the immunophenotype of

Pre-B-ALL and Mature B-ALL ?

A
  • Pre-B-ALL
    • CD10+/-
    • cytoplasmic IgM+
  • Mature B-ALL
    • surface IgM+
    • Note:
      • majority of mature B-ALL with expression of surface Ig are classified as Burkitt lymphoma in leukemic phase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are some differentiating flow findings

to help separate B-ALL from Hematogones ?

A
  • FSC vs. SSC properties of B-ALL
  • presence of aberrant CD13 or CD33
  • lack or very dim expression of CD45
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which B cell lymphomas can show a lack

of surface Ig expression ?

A
  • Follicular lymphoma
  • CLL
  • DLBCL
  • rarely HCL

Note:

  • they may also show dim or moderate expression of CD45
  • positive CD20, lack of blastic markers (TdT and CD34) and lack of bright CD10
    • favors a mature neoplasm
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the normal % of

hematogones in the marrow ?

A
  • ~1%
  • number decreases with age but may be increased in BMs from patients on chemotherapy
  • patients with MDS and MPNs
    • show a lack of hematogones
    • or at least decreased numbers of them
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

The phenotype of hematogones depends on their

developmental stage, how many stages are there and

what are their immunophenotypes ?

A

Usually all have very low SSC and variable FSC, smeary other markers

  • Stage I
    • positive: TdT, CD10, CD19, CD34, CD38 and CD58
  • Stage II
    • positive: CD10, CD19, CD38 and cytoplasmic IgM
    • negative: CD34, CD58 and TdT
  • Stage III
    • acquire dim (often variable) CD20
    • progressive loss of CD10

Note: CD45 expression and intensity increases from Stage I–> III

IMP: Stage II are predominant form (~65%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can CD34 and CD123 be used

to differentiate B-ALL from Hematogones ?

A
  • Discordant expression is seen in hematogones
    • Less mature hematogones (dim CD45+)
      • express CD34
      • lack CD123
    • more mature hematogones (moderate CD45+)
      • lack CD34
      • express CD123

IMP: blasts in B-ALL will have concordant expression of these markers

  • also hematogones do not express markers from different cell lines, eg CD13 and CD33
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the expression of TdT

in hematogones ?

A
  • hematogones have down-regulated TdT expression (from negative to dim)
  • B-ALL blasts usually have strong TdT but there are subsets that are negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the pattern of expression of CD10

in hematogones vs. B-ALL ?

A
  • much brighter inB-ALL
    • but subsets of B-ALL can be negative for CD10

IMP: in contrast, CD38 expression is bright in hematogones and more dim in B-ALL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the pattern of expression

for CD58 in B-ALL and hematogones ?

A
  • B-ALLs are positive for CD58
  • Hematogones
    • this antigen is only positive in the very early forms
    • majority of hematogones are negative
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How is T-ALL differentiated from

B-ALL by flow cytometry ?

A
  • positive for cCD3
    • sCD3 is usually negative
  • positive for:
    • CD2, CD5, and or CD7
    • at least 1 blastic marker, TdT, CD34 and or CD1a
  • Subset are positive for
    • CD71
    • CD123
  • CD45 is usually brighter than B-ALL
  • B cell markers are negative
  • CD10 is positive on at least a subset
    • but usually partial or dim
    • not bright like in B-ALL
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are some markers that B-ALL

and AML can have in common ?

A
  • AML cases can be positive for some B cell markers
    • esp CD19 but less often CD79a
  • B-ALL blasts can be positive for some myeloid markers
    • CD13, CD33
  • Both types of leukemia are positive for:
    • CD38
    • HLA-DR
    • Can also be positive for:
      • TdT
      • CD71
      • CD123
21
Q

How can AML be differentiated

from B-ALL?

A
  • AML is positive for CD117
    • strong expression of CD13 and CD33
    • strong MPO
    • lack of CD10 expression
  • AML with monocytic differentiation is positive for:
    • CD11b, CD11c, CD14, CD56, CD64 and CD123
  • Pure erythroid leukemia
    • CD71
    • Glycophorin A, Hemoglobin A
    • lacks B cell markers and CD10
22
Q

What is the definition of a mixed

phenotype acute leukemia (MPAL)?

A
  • the majority are myeloid/B and myeloid/T leukemias
  • they coexpress myeloid and lymphoid markers
  • MPALs are often positive for:
    • CD34, TdT, and HLA-DR
  • Myeloid lineage
    • confirmed by MPO (flow or IHC)
  • Monocytic lineage
    • need positive expression of at least 2 markers
      • CD11c
      • CD14
      • CD64, Lysozyme
      • Non-specific esterase
23
Q

How are the B and T cell lineages of an

MPAL confirmed ?

A
  • B cell lineage
    • bright CD19 expression, if dim you need either cCD22 or cCD79a
    • expression of CD10 can also be considered B cell lineage
  • T cell lineage
    • surface or cCD3
24
Q

In a B-ALL, what is there is MPO expression, does

that qualify for an MPAL ?

A
  • IF the B-ALL has a perfect immunophenotype with lack of CD13 and CD33
  • homogeneous expression of lymphoid markers
  • low level MPO
    • This does NOT qualify for an MPAL
25
Q

B-ALL vs. TdT+ B cell neoplasms with

BCL2 and or MYC rearrangements ?

A
  • occasionally mature B cell neoplasms can have blastic morphology and may represent a lymphoblastic transformation of a lower grade lymphoma like follicular
  • Suggested
    • TdT+ B cell lymphomas with BCL2 and or MYC rearrangment be classified as
      • High-grade TdT+ blastic B cell leukemia/lymphoma
      • they are very aggressive with poor prognosis
26
Q

In B-ALL, what is the single most powerful

clinical predictor of remission induction and duration

as well as long term survival ?

A
  • Total WBC count at the time of diagnosis
    • High WBC count is associated with extramedullary disease at diagnosis with high risk for relapse in the CNS and testes
  • Other important prognostic parameters include:
    • age at diagnosis
    • chromosomal abnormalities of the tumor
    • persistence of leukemia after induction
27
Q

Which B-ALL types are often positive

for t(9;22)?

A
  • Common B-ALL
  • pre-B-ALL
28
Q

Which B-ALL types are frequently

associated with t(4;11) ?

A
  • pro-B-ALL
29
Q

What patients typically have a poor prognosis?

A
  • adult patients with any of the following:
    • pre-B-ALL
    • t(4;11)
    • t(9;22)

Note: the absence of these shows a better outcome after intense chemotherapy

30
Q

What is true about CD10- pre-B-ALL ?

A
  • high risk subgroup in adult patients
  • associated with high frequency of KMT2A aberrations and worse prognosis
31
Q

What is true about pro-B and/or

t(4;11) ALL ?

A
  • associated with worse prognosis
  • but responds well to high dose cytarabine therapy and stem cell transplantation
32
Q

Which B-ALL subgroup tends to have variable

morphology ?

A
  • t(1;19)
  • blasts are larger with more irregular nuclei
  • basophilic cytoplasm and pronounced vacuoles
33
Q

What is the immunophenotype profile

of pro-B-ALL ?

A
  • aka early pre-B-ALL
  • CD10-
  • CD19+, TdT+
34
Q

What is the immunophenotype of

Common B-ALL ?

A
  • CD10+
  • CD19+
  • CD34+
  • TdT+
35
Q

What is the immunophenotype of

Pre-B-ALL ?

A
  • CD10+/-
  • cytoplasmic IgM+
  • CD34+/-
  • TdT+/-
36
Q

What is the immunophenotype of mature

B-ALL ?

A
  • surface IgM+
  • CD34-
  • TdT-

Note: if there is a MYC gene rearrangement these are considered to be Burkitt lymphoma in leukemic phase

37
Q

What is the immunophenotype of BCR-ABL1

B-ALL ?

A
  • bright CD10
  • CD11b+/-, CD13 (dim)+/-
  • CD15+/-
  • CD19+, CD20- (rarely+)
  • CD22+, CD25+, CD33+(dim, but may be negative)
  • CD34+/- (may be partial)
  • CD38+/-
  • CD45+(dim)/-
  • CD66c+, TdT+/-
38
Q

What is the immunophenotype of

MLL alterred B-ALL ?

A
  • CD10- (rare cases may be partially +)
  • CD15+(rare cases are negative)
  • CD19+, CD22+, CD33+/-
  • CD34+, CD65s+/-
  • TdT+/-

Note:

  • Occasional cases may show a mature B cell immunophenotype with clonal surface light chains, blastic morphology and lack of CD10, CD20, CD34 and TdT
39
Q

What marker can be used to differentiate B-ALL

from lymphomas of follicle center origin ?

A
  • CD10
    • usually quite bright in B-ALL
    • only moderate intensity in non-B-ALL
      • ex: follicular lymphoma
40
Q

What is the association of myeloid antigen

expression on B-ALL ?

A
  • associated with a worse prognosis
  • seen in:
    • BCR-ABL1
    • Balanced t(12;17)
    • extra copy of ETV6-RUNX1 fusion
  • usual markers expressed
    • CD33 >CD13
41
Q

How does the expression of

CD20 and CD45 in B-ALL

correlate with outcome?

A
  • CD45
    • intensity greater than 75th percentile
  • CD20
    • intensity greater than 25th percentile
    • adverse prognostic indicator, particularly with younger patients
    • Rituximab does improve the outcome
  • both significantly correlated with poor outcome independently
42
Q

What are poor prognostic factors in

adult B-ALL ?

A
  • elevated total WBC count (>50 x10^9/L)
  • t(9;22)
  • t(4;11)
  • t(1;19)
  • hypodiploidy
  • -7, +8
  • expression of myeloid antigens (CD13 and CD33)
  • persistent MRD
  • older age
43
Q

What are factors associaated with better

prognosis in adult B-ALL ?

A
  • age <30 years old
  • WBC count <30,000
  • t(10;14)
  • complete remission in 4 weeks
44
Q

In adult patients with BCR-ABL1 + B-ALL,

what additional cytogenetic abnormalities are frequently seen?

A
  • 67% of patients with B-ALL with BCR-ABL1 show additional cytogenetic aberrations including:
    • additional philadelphia chromosome
    • -7
    • +8
    • +X
    • del(9p)
45
Q

What is a very important risk predictor

for pediatric ALL patients?

A
  • MRD status is an independent prognostic factor that used for risk stratification
    • monitored by flow cytometry
      • IMP: hematogones are absent during the first few weeks of induction therapy, therefore, anything immature that is present likely represents residual disease
    • quantitative real time PCR looking for fusion transcripts
46
Q

What finding by flow cytometry is predictive

of an impending CNS relapse in B-ALL?

A
  • sample free of RBCs
  • TdT+ cells or cells with aberrant immunophenotype with negative cytology
47
Q

What is the differentiatl diagnosis for

B-ALL ?

A
  • Burkitt lymphoma, DLBCL
  • Follicular lymphoma
  • Mantle cell lymphoma, blastoid variant
  • PTCL
  • Plasma cell myeloma
  • Plasmablastic lymphoma
  • High-grade TdT+ blastic B cell lymphoma/leukemia with BCL2/MYC gene rearrangements
  • AML, MPAL
  • BPLL, TPLL
  • Metastatic carcinoma/Small round blue cell tumor
  • Hematogones
48
Q

What are some IHC markers for Small cell carcinoma

and Ewing’s sarcoma ?

A
  • Small cell carcinoma
    • panck, CD56, TTF1, high Ki67
  • Ewing’s sarcoma
    • CD99, FLI-1, Caveolin1, Leu7
    • Chromogranin, NSE and synaptophysin
49
Q

What are some IHC findings for

Rhabdomyosarcoma, Neuroblastoma and

Desmoplastic small round cell tumor ?

A
  • Rhabdomyosarcoma
    • MyoD1, myogenin, desmin, muscle specific actin
  • Neuroblastoma
    • NSE, chromogranin A
  • Desmoplastic small round blue cell tumor
    • keratins, EMA, desmin, NSE

Flow Cytometry (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions