|Year : 2014 | Volume
| Issue : 1 | Page : 187-190
A near tetraploid clone in acute myeloid leukemia with CD56 expression
Sandhya Devi Gundimeda1, Faiq Ahmed1, Manasi Chetan Mundada1, Senthil Jagannathan Rajappa2, Sudha S Murthy1
1 Department of Laboratory Medicine, Basavatarakam Indo-American Cancer Hospital and Research Institute, Banjara Hills, Hyderabad, Andhra Pradesh, India
2 Department of Medical Oncology, Basavatarakam Indo-American Cancer Hospital and Research Institute, Banjara Hills, Hyderabad, Andhra Pradesh, India
|Date of Web Publication||23-Apr-2014|
Sandhya Devi Gundimeda
Department of Laboratory Medicine, Basavatarakam Indo American Cancer Hospital and Research Institute, Road No. 14, Banjara Hills, Hyderabad - 500 034, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Acute myeloid leukemia (AML) is a heterogeneous disorder characterized by specific morphology, immunophenotype and genetic rearrangements. Multiple recurrent chromosomal aberrations have been identified by conventional cytogenetic analysis, which are now widely recognized as one of the most important diagnostic and prognostic determinants in AML. Here, we present a case with unusual cytogenetics, which has been described in very few patients.
Keywords: Acute myeloid leukemia, bizarre/large blasts, CD56 expression, near tetraploidy
|How to cite this article:|
Gundimeda SD, Ahmed F, Mundada MC, Rajappa SJ, Murthy SS. A near tetraploid clone in acute myeloid leukemia with CD56 expression. J Can Res Ther 2014;10:187-90
|How to cite this URL:|
Gundimeda SD, Ahmed F, Mundada MC, Rajappa SJ, Murthy SS. A near tetraploid clone in acute myeloid leukemia with CD56 expression. J Can Res Ther [serial online] 2014 [cited 2020 Feb 28];10:187-90. Available from: http://www.cancerjournal.net/text.asp?2014/10/1/187/131406
| > Introduction|| |
Acute myeloid leukemia (AML) is a heterogeneous disorder and 2008 World Health Organization classification of tumors of the hematopoietic and lymphoid neoplasms recommends identification of genetic abnormalities in addition to morphologic, immunophenotypic and clinical features to define the distinct subtypes of AML.  Conventional cytogenetics analysis plays an integral part in the diagnostic work-up of AML patients having a direct impact on the choice of treatment and patient prognosis.  Here, we present a patient with AML associated with a rare cytogenetic abnormality.
| > Case Report|| |
A 35 year old male with the morphological diagnosis of acute leukemia elsewhere presented for further management. He was admitted with complaints of fever, easy fatigability and pain in the abdomen for about a week. There was no history of bowel abnormalities, dysuria, vomiting or bleeding from any site. He had loss of appetite, but there was no history of weight loss. On clinical examination, his performance status was 2, he was pale, febrile, there were no purpura or petechiae, gum hypertrophy or bony tenderness, jaundice, hepatosplenomegaly or lymphadenopathy. The cardiovascular, respiratory and nervous system examination were unremarkable.
The peripheral smear showed red blood cells to be normocytic and normochromic, total leucocyte counts 1.7 × 10 3 cells/μl, with 43% comprising circulating blasts and 57% lymphocytes and reduced platelet counts 28 × 10 3 /μl. Blasts were 5-6 times the size of a mature lymphocyte with high N:C ratio, with nuclei showing 2-3 nucleoli [Figure 1] and [Figure 2]. Cytochemical stains for myeloperoxidase and Periodic Acid Schiff were negative.
|Figure 1: Peripheral smear of an acute myeloid leukemia with minimal differentiation case showing large blasts (Leishman stain, oil immersion ×100)|
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Immunophenotyping was performed on peripheral blood using lyse/wash technique. The gated population of cells was moderately positive for CD45, CD34, CD33, CD117, CD56, bright positive for HLA-DR and negative for B and T cell markers [Figure 3]. The antigenic expression profile was consistent with the diagnosis of AML with minimal differentiation (AML-M0) and aberrant CD56 expression.
|Figure 3: The gated population of neoplastic cells showed positivity for -HLA-DR, CD45, CD34, CD33, CD117, CD56 and negative for B and T cell markers|
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Conventional cytogenetic analysis was performed on unstimulated peripheral blood. Metaphase chromosomes were G-banded with trypsin-Giemsa and karyotyped in accordance with the international system of human cytogenetic nomenclature (ISCN, 2005).  Chromosome analysis showed near tetraploid clone (4n+/−) in six metaphases and normal karyotype in three metaphases [Figure 4]a and b. Only one metaphase amenable to karyotyping showed the following karyotype:
90 <4n>, XY, −X, −Y, −1, −4, −4, −5, +6, −9, −10, −12, −12, +13, +14, +15, +16, +17, +17, +20 [Figure 5].
|Figure 4: (a and b) A case of acute myeloid leukemia with the minimal differentiation. Metaphases show near tetraploidy|
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|Figure 5: Karyotype shows 90<4n>, XY, −X, −Y, −1, −4, −4, −5, +6, −9, −10, −12, −12, +13, +14, +15, +16, +17, +17, +20|
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Although chemotherapy with standard 7 + 3 regimen was started, the patient could not tolerate the chemotherapy and hence was discontinued after 3 days. He was discharged and since then has been lost for follow-up.
| > Discussion|| |
Here, we present a young adult with de novo AML-M0, showing few polyploid cells with near-tetraploidy, which constitutes a rare presentation defined by blasts containing 80-104 chromosomes.  The near tetraploid metaphase amenable to karyotyping showed only gain and losses of chromosomes and lacked any of the recurrent genetic abnormalities associated with AML. The chromosomes in the other near tetraploid metaphases were clustered and individual chromosomes defied analysis owing to the fuzzy appearance. Coexistence of both normal and near tetraploid metaphases was evident.
Near-tetraploidy has been described in myelodysplastic syndrome, carcinomas, acute lymphoblastic leukemia and at presentation in de novo AML cases. The abnormality is rare and described in 0.98-1.2% of all AML patients. ,, Until date, less than 70 cases have been described in the literature. , Our finding is consistent with the low frequency of near tetraploidy/tetraploidy in AML.
Tetraploidy or near tetraploidy in AML, maybe a progressive secondary karyotypic change often accompanied by additional chromosomal abnormalities such as cases with a single marker chromosome, complex karyotypic abnormalities including numerical abnormalities of chromosomes 5, 7, or both, 1, 2, 3 and 17 or structural rearrangements such as double t (8;21)(q22;q22) in AML-M2, duplication of t (15;17) in AML-M3. Coexistence of normal metaphases with near tetraploid clones has been described earlier.  Confirmation of specific genetic abnormalities characteristic of different subtypes of AML by fluorescence in situ hybridization was negative.  Association of FMS-like tyrosine kinase 3(FLT3) and other gene mutations etiologic of chromosomal instability also has been described.  Previous studies reported that molecular events such as the loss or inactivation of tumor protein 53(TP53) can cause a premature round of deoxyribonucleic acid (DNA) synthesis and mitotic arrest, leading to polyploidy. A global defect in cell cycle control may lead to endoreduplication or nuclear mitotic division, but the exact mechanism is not yet known. 
Near tetraploidy has been reported to be associated with different morphological French-American-British subtypes of AML and with large bizarre blasts. ,, Although DNA content was not evaluated in the present case, Kwong and Wong (1995) demonstrated that in hyperdiploid myeloid leukemias, increase in DNA content is accompanied by a corresponding increase in blast size.  As observed in the present case [Figure 4] if large and bizarre blasts are seen on morphologic analysis, polyploid metaphases in cytogenetic preparations should be expected.
Immunophenotyping is routinely applied in acute leukemia diagnostics and is complementary to morphological, cytochemical and karyotypic studies, allowing for a more precise diagnosis, classification of AML and prognostication. The review of immunophenotype of 25 AML M0-M5 AML patients, indicated variable expression of CD56 in 33% cases.  Although, Jurisic et al. (2009) immunophenotyped the 4 near tetraploid cases, role of CD56 in these cases was not investigated. 
The scatter gram in the present case depicted positivity for myeloid markers along with CD56 expression. CD56 antigen, a 200-220 kDa cell surface glycoprotein, an isoform of the neural adhesion molecules, has been found frequently expressed in several lympho-hematopoietic neoplasms including AML. The prognostic significance of CD56 is debated.  However the presence of CD56 antigen on the blasts of AML patients with t (8;21)(q22;q22) and in those with M3 subtype, identifies a subgroup of patients with a more unfavorable prognosis. Morphologically when large bizarre blasts are evident and immunophenotype shows aberrant expression of CD56, association of near tetraploidy can be suspected.
While some reports described the outcome of these patients to be poor,  variable, , after standard chemotherapy, Bιnι et al. (2006) showed that patients with de novo near tetraploid AML might benefit from therapy with intermediate or high doses of cytosine arabinoside combined with anthracyclines for complete remission (CR) induction and/or consolidation, followed by autologous stem cell transplantation in first CR. 
To the best of our knowledge, this is the first reported case of rare chromosome number aberration near tetraploidy without structural aberrations in de novo AML-M0 from India. Pleomorphic morphology, characterized by unusually large blasts with aberrant expression of CD56 immunophenotypically warrants confirmation of near tetraploidy/tetraploidy. Further study of more cases of tetraploid AML will be of great importance in understanding the clinical, biological, prognosis of this group of patients.
| > Acknowledgments|| |
We would like to thank Mrs. A. Parameshwari, Mr. K. Ramchander Reddy, Mrs. M. Padma for the technical support extended.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]