Abstract
Infants with Down syndrome have increased incidences of transient abnormal myelopoiesis (TAM) and acute leukemia, which are usually associated with acute megakaryoblastic leukemia (AMKL). A 5-day-old girl with Down syndrome was diagnosed with TAM; 4 months later, acute leukemic transformation was suspected. Bone marrow (BM) examination was performed, and the infant was diagnosed with acute leukemia (80% blasts). Although BM aspirates showed the presence of megakaryocytic blasts with cytoplasmic blebs, flow cytometry analysis revealed that they were negative for cells with CD41a and CD61 immunophenotypes. Further analysis revealed that the megakaryocyte-related marker CD42a was positive in 57% of blasts. Morphologic and immunophenotypic features are required to establish the lineage of megakaryocytic blasts, which are necessary for diagnosing AMKL. As most cases of AMKL were positive for CD41 and/or CD61 markers, their presence was evaluated during routine analysis. In order to identify the immunophenotypic features of AMKL in an infant with Down syndrome, we performed additional flow cytometry for CD42a, one of the megakaryocytic markers, and were able to assist in the early diagnosis of AMKL, as well as to use CD42a as an effective follow-up marker.
Figures and Tables
Fig. 2
Flow cytometric analysis showing blast expression with CD41a-/CD61-/CD42a+ immunophenotypes. (A) Almost all leukemic cells showed strong positive expression of CD117, but were negative for CD61. (B) Many leukemic cells were negative for CD41a, but showed positive expression of CD42a. (C) Many leukemic cells showed aberrant expression of CD7.
![lmo-4-112-g002](/upload/SynapseData/ArticleImage/0192lmo/lmo-4-112-g002.jpg)
References
1. Zipursky A. Transient leukaemia--a benign form of leukaemia in newborn infants with trisomy 21. Br J Haematol. 2003; 120:930–938.
![crossref](/image/icon/bnr_ref_cross.gif)
![crossref](/image/icon/bnr_ref_cross.gif)
2. Klusmann JH, Creutzig U, Zimmermann M, Dworzak M, Jorch N, Langebrake C, et al. Treatment and prognostic impact of transient leukemia in neonates with Down syndrome. Blood. 2008; 111:2991–2998.
![crossref](/image/icon/bnr_ref_cross.gif)
![crossref](/image/icon/bnr_ref_cross.gif)
3. Massey GV, Zipursky A, Chang MN, Doyle JJ, Nasim S, Taub JW, et al. A prospective study of the natural history of transient leukemia (TL) in neonates with Down syndrome (DS): Children's Oncology Group (COG) study POG-9481. Blood. 2006; 107:4606–4613.
![crossref](/image/icon/bnr_ref_cross.gif)
![crossref](/image/icon/bnr_ref_cross.gif)
4. Muramatsu H, Kato K, Watanabe N, Matsumoto K, Nakamura T, Horikoshi Y, et al. Risk factors for early death in neonates with Down syndrome and transient leukaemia. Br J Haematol. 2008; 142:610–615.
![crossref](/image/icon/bnr_ref_cross.gif)
![crossref](/image/icon/bnr_ref_cross.gif)
6. Tomer A. Human marrow megakaryocyte differentiation: multiparameter correlative analysis identifies von Willebrand factor as a sensitive and distinctive marker for early (2N and 4N) megakaryocytes. Blood. 2004; 104:2722–2727.
![crossref](/image/icon/bnr_ref_cross.gif)
![crossref](/image/icon/bnr_ref_cross.gif)
7. Swerdlow SH, Campo E, editors. WHO classification of tumours of haematopoietic and lymphoid tissues. 4th ed. Lyon: International Agency for Research on Cancer;2008.
8. Seewald L, Taub JW, Maloney KW, McCabe ER. Acute leukemias in children with Down syndrome. Mol Genet Metab. 2012; 107:25–30.
![crossref](/image/icon/bnr_ref_cross.gif)
![crossref](/image/icon/bnr_ref_cross.gif)