Letter to the Editor:
Lineage determination in acute leukemias
Natália Aydos Marcondes1*, Flavo Beno Fernandes1, Gustavo Adolpho Moreira Faulhaber1,2
1
Laboratório Zanol, Porto Alegre, Brazil
2 Professor – Medical Sciences Post graduation Program – Federal University of Rio Grande do Sul
* Adress for correspondence: Natália Aydos Marcondes Laboratório Zanol, Rua Mostardeiro, 333/120, 90430-001, Porto Alegre, Brazil e-mail: [email protected] Fone: +55 51 35331020, fax: +55 51 35331290
Keywords: T-lymphoblastic leukemia/lymphoma, mixed phenotype leukemia T/myeloid, myeloperoxidase expression
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as an ‘Accepted Article’, doi: 10.1002/cytob.21146
Cytometry: Part B - Clinical Cytometry
Lineage determination in acute leukemias
Dear Editor,
We read with great interest the Case Study Interpretation Section (CSI) in the last issue of Cytometry Part B. We perform flow cytometry tests and it is always constructive to challenge our analysis and interpretation skills.
Case 2 of the CSI, reported by Weina Chen (1), describes a case of an acute leukemia diagnosed as mixed phenotype leukemia T/myeloid. According to the World Health Organization (WHO), myeloperoxidase (MPO) or at least two markers of monocytic differentiation, are required to assign the lineage of a blast population as myeloid, although it does not establishes a minimum percent of myeloid population for the leukemia to be considered of mixed phenotype (2). In the immunophenotypic analysis of the case only ~3% of the blasts expressed cytoplasmatic MPO (cMPO). This small subset of blasts could represent normal myelod progenitor cells since this population was in the compartment where it would be expected to have non-malignant myeloid blasts (3), and there was no evidence of cytoplasmatic CD3 co-expression in the FCS files. Also, in the lymph node biopsy, the cells largely lacked MPO and it could have been expressed in myeloid cells instead of blasts.
2 John Wiley and Sons, Inc.
Page 2 of 4
Page 3 of 4
Cytometry: Part B - Clinical Cytometry
As suggested recently, a threshold of 10% for cMPO staining detected by flow cytometry in blast cells would be a secure lower limit for the expression of this marker and subsequent classification of the leukemia as myeloid lineage (3). We believe that a 10% positivity for flow cytometric analysis would be a good choice for the classification of the leukemia as mixed phenotype as well (4). Although mixed phenotype acute leukemias are rare, more studies are needed in order to make possible the definition of a minimum percentage of expression for lineage determination. These objective evidences are important to define more precise criteria in the next edition of WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues.
Sincerely,
Natália Aydos Marcondes, MSc Flavo Beno Fernandes, MD Gustavo Adolpho Moreira Faulhaber, MD PhD
Laboratório Zanol, Rua Mostardeiro, 333/120, 90430-001, Porto Alegre, Brazil e-mail: [email protected] Tel +55 51 35331020, fax +55 51 35331290
Conflict of interest
3 John Wiley and Sons, Inc.
Cytometry: Part B - Clinical Cytometry
The authors declared that they have no conflict of interest.
LITERATURE CITED
1.
Chen W. Case study interpretation-New Orleans: case 2. Mixed
phenotype acute leukemia, T/myeloid. Cytometry B Clin Cytom. 2013 SepOct;84(5):342-5. 2.
Swerdlow SH, International Agency for Research on Cancer., World
Health Organization. WHO classification of tumours of haematopoietic and lymphoid tissues. 4th ed. Lyon, France: International Agency for Research on Cancer; 2008. 3.
van den Ancker W, Westers TM, de Leeuw DC, van der Veeken YF,
Loonen A, van Beckhoven E, et al. A threshold of 10% for myeloperoxidase by flow cytometry is valid to classify acute leukemia of ambiguous and myeloid origin. Cytometry B Clin Cytom. 2013 Mar;84(2):114-8. 4.
Hoehn D, Medeiros LJ, Chen SS, Tian T, Jorgensen JL, Ahmed Y, et
al. CD117 expression is a sensitive but nonspecific predictor of FLT3 mutation in T acute lymphoblastic leukemia and T/myeloid acute leukemia. Am J Clin Pathol. 2012 Feb;137(2):213-9.
4 John Wiley and Sons, Inc.
Page 4 of 4
Lineage determination in acute leukemias
Natália Aydos Marcondes1*, Flavo Beno Fernandes1, Gustavo Adolpho Moreira Faulhaber1,2
1
Laboratório Zanol, Porto Alegre, Brazil
2 Professor – Medical Sciences Post graduation Program – Federal University of Rio Grande do Sul
* Adress for correspondence: Natália Aydos Marcondes Laboratório Zanol, Rua Mostardeiro, 333/120, 90430-001, Porto Alegre, Brazil e-mail: [email protected] Fone: +55 51 35331020, fax: +55 51 35331290
Keywords: T-lymphoblastic leukemia/lymphoma, mixed phenotype leukemia T/myeloid, myeloperoxidase expression
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as an ‘Accepted Article’, doi: 10.1002/cytob.21146
Cytometry: Part B - Clinical Cytometry
Lineage determination in acute leukemias
Dear Editor,
We read with great interest the Case Study Interpretation Section (CSI) in the last issue of Cytometry Part B. We perform flow cytometry tests and it is always constructive to challenge our analysis and interpretation skills.
Case 2 of the CSI, reported by Weina Chen (1), describes a case of an acute leukemia diagnosed as mixed phenotype leukemia T/myeloid. According to the World Health Organization (WHO), myeloperoxidase (MPO) or at least two markers of monocytic differentiation, are required to assign the lineage of a blast population as myeloid, although it does not establishes a minimum percent of myeloid population for the leukemia to be considered of mixed phenotype (2). In the immunophenotypic analysis of the case only ~3% of the blasts expressed cytoplasmatic MPO (cMPO). This small subset of blasts could represent normal myelod progenitor cells since this population was in the compartment where it would be expected to have non-malignant myeloid blasts (3), and there was no evidence of cytoplasmatic CD3 co-expression in the FCS files. Also, in the lymph node biopsy, the cells largely lacked MPO and it could have been expressed in myeloid cells instead of blasts.
2 John Wiley and Sons, Inc.
Page 2 of 4
Page 3 of 4
Cytometry: Part B - Clinical Cytometry
As suggested recently, a threshold of 10% for cMPO staining detected by flow cytometry in blast cells would be a secure lower limit for the expression of this marker and subsequent classification of the leukemia as myeloid lineage (3). We believe that a 10% positivity for flow cytometric analysis would be a good choice for the classification of the leukemia as mixed phenotype as well (4). Although mixed phenotype acute leukemias are rare, more studies are needed in order to make possible the definition of a minimum percentage of expression for lineage determination. These objective evidences are important to define more precise criteria in the next edition of WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues.
Sincerely,
Natália Aydos Marcondes, MSc Flavo Beno Fernandes, MD Gustavo Adolpho Moreira Faulhaber, MD PhD
Laboratório Zanol, Rua Mostardeiro, 333/120, 90430-001, Porto Alegre, Brazil e-mail: [email protected] Tel +55 51 35331020, fax +55 51 35331290
Conflict of interest
3 John Wiley and Sons, Inc.
Cytometry: Part B - Clinical Cytometry
The authors declared that they have no conflict of interest.
LITERATURE CITED
1.
Chen W. Case study interpretation-New Orleans: case 2. Mixed
phenotype acute leukemia, T/myeloid. Cytometry B Clin Cytom. 2013 SepOct;84(5):342-5. 2.
Swerdlow SH, International Agency for Research on Cancer., World
Health Organization. WHO classification of tumours of haematopoietic and lymphoid tissues. 4th ed. Lyon, France: International Agency for Research on Cancer; 2008. 3.
van den Ancker W, Westers TM, de Leeuw DC, van der Veeken YF,
Loonen A, van Beckhoven E, et al. A threshold of 10% for myeloperoxidase by flow cytometry is valid to classify acute leukemia of ambiguous and myeloid origin. Cytometry B Clin Cytom. 2013 Mar;84(2):114-8. 4.
Hoehn D, Medeiros LJ, Chen SS, Tian T, Jorgensen JL, Ahmed Y, et
al. CD117 expression is a sensitive but nonspecific predictor of FLT3 mutation in T acute lymphoblastic leukemia and T/myeloid acute leukemia. Am J Clin Pathol. 2012 Feb;137(2):213-9.
4 John Wiley and Sons, Inc.
Page 4 of 4
