Transcript Slide 1

ICCS e-newsletter CSI
Spring 2012
Weina Chen, MD, PhD
Medical Director, Hematopathology
Ameripath/Quest Diagnostics
Dallas, Texas
Case History
The patient is a 70-year old female presented with mild
leukocytosis. She has no prior history of any significant
diseases and is asymptomatic.
Complete blood count
WBC 10.70
NE 50%
LY 39.4%
MO 9.3%
EO 0.7%
BASO 0.6%
RBC 4.41
HGB 12.7
HCT 37.7%
MCV 85.5
MCHC 33.70
RDW 12.6
PLT 211.0
Work-up and evaluation
Bone marrow (BM) aspirate and biopsy were procured.
Flow cytometric analysis was performed on marrow
aspirate and results from selected 4-color tubes are
provided for review.
Flow cytometric analysis
• Acquisition Beckman Coulter Epics XL (FCS2.0, System II)
• Analyzed by Paint-A-Gate software (adapted to Coulter)
• Tubes (FITC/PE/ECD/PC5)
– Tube 1: Kappa/lambda/45/19+20
– Tube 2: 5/19/45/10
– Tube 3 : 8/4/45/38
– Tube 4: 15/117/45/34
– Tube 5: 20/10/19/38
– Tube 6: FMC-7/23/5/19
– Tube 7: Kappa/Lambda/5/19
Tube 1: Kappa/lambda/45/19+20
A population of (CD19/20)+ B cells divided into
3 subsets based on intensity of CD45
• Blue (strong CD45)
(intermediate CD45)
(dim CD45)
Tube 1: Kappa/lambda/45/19+20
CD(19/20)+ B cells showing variable, polytypic light
chain expression
• Blue (strong CD45): polytypic surface Ig expression
(intermediate CD45): a subset polytypic sIg
(dim CD45): no surface Ig
Tube 2: 5/19/45/10
Differential expression of CD5 and CD10 on 3 subsets of B cells
• Blue (subset CD5+, CD10-)
•
(CD5-, CD10+)
•
(CD5-, CD10bright+)
Tube 3 : 8/4/45/38
Differential expression of CD38 on 3 subsets of B cells
• Blue (CD38variable/partial +)
•
(CD38uniform strong +)
•
(CD38+)
Tube 4: 15/117/45/34
Differential expression of CD34 on 3 subsets of B cells
• Blue (CD34-)
•
(CD34-)
•
(CD38+)
Of note, myeloblasts in red express CD117 and CD34
Tube 5: 20/10/19/38
Differential expression of CD10, 20 and CD38 on 3 subsets of
CD19(+) B cells
• Blue (CD10-, CD20+, CD38variably/partial+)
•
(CD10+, CD20variably+, CD38uniform +)
•
(CD10bright+, CD20-, CD38+)
Tube 6: FMC-7/23/5/19
Differential expression of CD5, CD23 and FMC7 on 3 subsets of
CD19(+) B cells
• Blue (CD5subset+, CD23partial +, FMC7+)
•
(CD5subset+, CD23-, FMC7-)
•
(CD5-, CD23-, FMC7-)
Tube 7: Kappa/Lambda/5/19
Differential expression of surface Ig and CD5 on subsets of
CD19(+) B cells
• Blue (CD5+, sIgpolytypic)
•
(CD5predominantly -, sIg-)
[In addition, CD13-, CD33- (data not shown); Tdt not tested]
Key flow plots in this case
CD19(+)/CD20(+) B cells overall exhibiting a pattern
of sequential maturation
Morphologic evaluation
Marrow infiltrated by abundant small to medium-sized lymphoid cells with
mature morphologic features although nuclear irregularity/convolution and
small cytoplasmic vacuoles observed in a few scattered lymphoid cells.
Immunohistochemical evaluation
CD20
CD79a
Tdt
CD34
CD10
A prominent CD79a(+) B-lymphoid hyperplasia of mostly CD10(+) B lymphocytes
with increased Tdt(+) cells, some in clusters exceeding 3 or 4 cells
Questions…
• There is an expansion of B cells overall
exhibiting a spectrum of maturation.
• Are these normal maturing B-cell precursors
(hematogones) or B-lymphoblasts?
A few words on hematogones…
• Hematogones always express consistent, reproducible, complex
spectrum of sequential antigen expression and lack aberrant antigen
expression.
• This defines hematogones into three stages of maturation
– Stage 1 hematogones express CD34, high levels of CD10 and CD38, a
moderate level of CD22, and absence of CD20.
– Intermediate stage 2 hematogones downregulate CD34 completely and
CD10 partially, while increasing expression of CD22 and CD20.
– Stage 3 hematogones upregulate CD20 expression reaching the intensity of
mature B cells, and CD10 and CD38 are slightly down-regulated with
increasing expression of polytypic surface immunoglobulin light chains.
– Subsequently, these cells mature into CD20(+), CD10(-) mature B cells.
– CD5 is expressed on normal, polytypic B cells in a continuum, predominantly
at later stages of maturation, specifically on stage 3 hematogones and
mature B cells.
Comparison to a case with hematogone hyperplasia
A case with hematogone (HG) hyperplasia case (bottom plots):
Blue, mature B cells; Green, stage 2+3 HG; yellow, stage I HG
Comparison to a case with hematogone hyperplasia
A case with hematogone (HG) hyperplasia case (bottom plots):
Blue, mature B cells; Green, stage 2+3 HG; yellow, stage I HG
Questions…
• These B cells exhibit a spectrum of
maturation reminiscent of hematogones and
unusual for neoplastic lymphoblasts.
• Are these hematogones???
Answer…
• No
• These are B-lymphoblasts.
• The key finding in this case (on BM sample)
– Cytogenetics: 46, XX, t(9;22)(q34;q11.2)[17]/46, XX [3]
– Positive FISH for t(9;22)/BCR-ABL1 in 79% of
interphase cells
Answer…
• Differential diagnosis
– An early chronic myelogenous leukemia (CML) with
background hematogone hyperplasia (but the usual
morphologic features of CML not apparent)
– Lymphoid blast crisis of CML (but no history of CML)
– An early B-lymphoblastic leukemia with
t(9;22)(q34;q11.2);BCR-ABL1
Favored Diagnosis
B-lymphoblastic leukemia with
t(9;22)(q34;q11.2);BCR-ABL1
Based on the high percent of t(9;22) positive cells
(~70%), the entire B-cell population or the majority of B
cells including polytypic B cells seems neoplastic.
A few words on B-lymphoblastic leukemia
with t(9;22)(q34;q11.2);BCR-ABL1
• The most frequently observed chromosomal abnormality in adult BALL (25% vs. 3-5% in children)
• Involving the ABL1 oncogene on chromosome 9 and the guanosine
triphosphate–binding protein BCR on chromosome 22
• The resultant fusion protein having abnormal tyrosine kinase activity,
leading to disturbances in proliferation, survival, and adhesion
• In about 70% of cases of BCR-ABL1+ B-ALL, the expressed protein
being 190 kDa, rather than the 210 kDa typically seen in CML
• Associated with a poor prognosis in both children and adults
Unusual features in this case
• Unusual presentation: close to normal CBC with differential
at presentation
• Unusual morphology: mature morphologic features with mild
cytological atypia
• Unusual immunophenotype: maturation spectrum
reminiscent of hematogones (with only subtle deviation)
• Unusual, indolent clinical course
– Follow-up BM in 5 months (with only imatinib mesylate tx)
• Close to normal CBC, asymptomatic
• Persistent, but decreased B-lymphoblasts (similar
phenotype)
• RT-PCR: positive BCR-ABL1, p190, further supporting BALL
What are the clues to avoid misdiagnosis?
• No apparent causes for hematogone hyperplasia
• Common causes for hematogone hyperplasia:
• Reactive conditions: AIDS, immune dysregulation,
copper deficiency), BM involved by metastatic tumors
• Regenerative conditions: post-chemotherapy and stemcell transplant
• Relatively high number of hematogones in children
• Subtle immunophenotypic deviation from hematogones
• Less distinct “ladder” of CD45 on subsets of B cells
• Tdt positive cells, some in clusters exceeding 3 or 4 cells
• The need to add new markers to distinguish hematogones
from lymphoblasts
• CD81, CD123
Take home messages
• The immunophenotype of B-lymphoblasts is variable.
• While the majority of cases having distinct immunophenotypic
aberration deviated from hematogones, rare cases with
immunophenotypic feature reminiscent of hematogones do exist.
• Careful immunophenotypic analysis, clinical correlation for
causes
of
hematogone
hyperplasia,
ancillary
studies
(cytogenetics, FISH/molecular studies) are the key elements to
reach a correct diagnosis.
References
1. Weir EG, Cowan K, LeBeau P, Borowitz MJ. A limited antibody panel can distinguish B-precursor
acute lymphoblastic leukemia from normal B precursors with four color flow cytometry: implications for
residual disease detection. Leukemia 1999;13:558-67.
2. McKenna RW, Washington LT, Aquino DB, Picker LJ, Kroft SH. Immunophenotypic analysis of
hematogones (B-lymphocyte precursors) in 662 consecutive bone marrow specimens by 4-color flow
cytometry. Blood 2001;98:2498-507.
3. McKenna RW, Asplund SL, Kroft SH. Immunophenotypic analysis of hematogones (B-lymphocyte
precursors) and neoplastic lymphoblasts by 4-color flow cytometry. Leuk Lymphoma 2004;45:277-85.
4. Chen W, Karandikar NJ, McKenna RW, Kroft SH. Stability of leukemia-associated immunophenotypes
in precursor B-lymphoblastic leukemia/lymphoma: a single institution experience. Am J Clin Pathol
2007;127:39-46.
5. Seegmiller AC, Kroft SH, Karandikar NJ, McKenna RW. Characterization of immunophenotypic
aberrancies in 200 cases of B acute lymphoblastic leukemia. Am J Clin Pathol 2009;132:940-9.
6. Loken MR, Shah VO, Dattilio KL, Civin CI. Flow cytometric analysis of human bone marrow. II.
Normal B lymphocyte development. Blood 1987;70:1316-24.
7. Ryan DH, Chapple CW, Kossover SA, Sandberg AA, Cohen HJ. Phenotypic similarities and
differences between CALLA-positive acute lymphoblastic leukemia cells and normal marrow CALLApositive B cell precursors. Blood 1987;70:814-21.
8. Campana D, Coustan-Smith E. Detection of minimal residual disease in acute leukemia by flow
cytometry. Cytometry 1999;38:139-52.
9. Fuda FS, Karandikar NJ, Chen W. Significant CD5 expression on normal stage 3 hematogones and
mature B Lymphocytes in bone marrow. Am J Clin Pathol 2009;132:733-7.
10. Hurwitz CA, Gore SD, Stone KD, Civin CI. Flow cytometric detection of rare normal human marrow
cells with immunophenotypes characteristic of acute lymphoblastic leukemia cells. Leukemia 1992;6:233-9.
11. Hurwitz CA, Loken MR, Graham ML, et al. Asynchronous antigen expression in B lineage acute
lymphoblastic leukemia. Blood 1988;72:299-307.
12. Kurec AS, Belair P, Stefanu C, Barrett DM, Dubowy RL, Davey FR. Significance of aberrant
immunophenotypes in childhood acute lymphoid leukemia. Cancer 1991;67:3081-6.
13. Muzzafar T, Medeiros LJ, Wang SA, Brahmandam A, Thomas DA, Jorgensen JL. Aberrant
underexpression of CD81 in precursor B-cell acute lymphoblastic leukemia: utility in detection of minimal
residual disease by flow cytometry. Am J Clin Pathol 2009;132:692-8.
14. Hassanein NM, Alcancia F, Perkinson KR, Buckley PJ, Lagoo AS. Distinct expression patterns of
CD123 and CD34 on normal bone marrow B-cell precursors ("hematogones") and B lymphoblastic
leukemia blasts. Am J Clin Pathol 2009;132:573-80.
15. Muehleck SD, McKenna RW, Gale PF, Brunning RD. Terminal deoxynucleotidyl transferase (TdT)positive cells in bone marrow in the absence of hematologic malignancy. Am J Clin Pathol 1983;79:277-84.
16. Rimsza LM, Larson RS, Winter SS, et al. Benign hematogone-rich lymphoid proliferations can be
distinguished from B-lineage acute lymphoblastic leukemia by integration of morphology,
immunophenotype, adhesion molecule expression, and architectural features. Am J Clin Pathol
2000;114:66-75.
17. Sutton L, Vusirikala M, Chen W. Hematogone hyperplasia in copper deficiency. Am J Clin Pathol
2009;132:191-9; quiz 307.