|Year : 2017 | Volume
| Issue : 2 | Page : 61-67
The pheno-genotypic characteristics of infantile acute leukemia in a regional cancer center from South India
Divya Vijayanarasimha1, DS Madhumathi2, Prasanna Kumari3, Jayadeva Naik4, L Appaji5, V Lakshmidevi6
1 Fellow in Department of Pathology, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
2 HOD Department of Flowcytometry, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
3 HOD Department of Cytogenetics, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
4 Department of Flowcytometry, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
5 HOD Department of Pediatric Oncology, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
6 HOD Department of Pathology, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
|Date of Web Publication||17-Jul-2017|
33/A, Ragvilas Society, Lane C, Koregaon Park, Pune 411 001, Maharashtra
Source of Support: None, Conflict of Interest: None
Introduction: Acute leukemia (AL) is uncommon in infants, with an annual incidence of 30 per million live births. They have peculiar biological characteristics. Although remarkable progress is seen in treatment of childhood AL, infantile AL remains a resistant subset with a dismally low 4-year survival of 35%.
Objectives: To study the morphological, immunophenotypic, and cytogenetic features of infantile AL. A retrospective study of AL cases in children from birth up to 1 year of age, presenting to the departments of pediatric oncology and hematopathology between January 2010 and April 2015, was conducted.
Results: Thirty-eight cases of infantile AL were included. The mean age at presentation was 10.2 months, and a female preponderance (M–F ratio: 0.65:1) was noted. Hyperleukocytosis (total white cell count >50 × 109/mm3) was seen in 13 (39.4%) cases. Immunophenotyping done in 31 cases showed pre-B acute lymphoblastic leukemia (B ALL) in 18 (58%), pre-T ALL in three (9.7%), and acute myeloid leukemia (AML) in 10 (32.3%). CD10 positivity was seen in 12 (57.1%) cases of ALL. Cytogenetic study done in 34 cases showed AML with recurrent genetic abnormalities in four. Mixed lineage leukemia (11q23) abnormality was seen in three cases of ALL. Two cases of AML were associated with trisomy 21. One case with features of AML M7 in a 4-day-old baby turned out to be transient abnormal myelopoiesis on follow-up.
Conclusion: Literature on infantile AL from Indian studies is scarce compared to the available Western literature. Hence an epidemiological study of AL cases was done with review of literature, in an attempt to understand their pheno-genotypic features that influence their behavior. This may help in standardizing the treatment of these rare cases.
Keywords: Cytogenetics in infantile acute leukemia, immunophenotyping in infantile leukemia, infantile leukemia
|How to cite this article:|
Vijayanarasimha D, Madhumathi D S, Kumari P, Naik J, Appaji L, Lakshmidevi V. The pheno-genotypic characteristics of infantile acute leukemia in a regional cancer center from South India. J Appl Hematol 2017;8:61-7
|How to cite this URL:|
Vijayanarasimha D, Madhumathi D S, Kumari P, Naik J, Appaji L, Lakshmidevi V. The pheno-genotypic characteristics of infantile acute leukemia in a regional cancer center from South India. J Appl Hematol [serial online] 2017 [cited 2017 Aug 19];8:61-7. Available from: http://www.jahjournal.org/text.asp?2017/8/2/61/210830
| Introduction|| |
Acute leukemias (ALs) are uncommon in infants with an incidence of 30 cases per million live births. The annual incidence of acute lymphoblastic leukemia (ALL) (20 per million) is almost twice the rate of acute myeloid leukemia (AML) (10.6 per million). They have unique epidemiological, biological, and clinical characteristics.
Although remarkable progress has been seen in treatment of childhood ALL, achieving cure rates of nearly 80%, infantile AL remains a resistant subset with an extremely poor prognosis, having an event-free survival of 33 to 39% at 4 years. Therapeutic efforts in infantile AL center on intensification and determining relevant prognostic factors to identify infants needing the most aggressive therapy.
In this study, we describe the clinical, hematological, immunophenotypic, and cytogenetic spectrum of infantile AL cases.
| Materials and Methods|| |
Children up to 1 year of age diagnosed with AL by peripheral blood smear (PBS) and bone marrow (BM) examination between January 2010 and April 2015 were included in the study. Data were collected retrospectively from the medical records section, departments of pediatric oncology, hematopathology, and cytogenetics.
The following clinical details were collected: relevant symptoms and signs including presence or absence of pallor, petechiae, lymphadenopathy, organomegaly, and features of extramedullary involvement. The hemogram, findings of detailed PBS examination, and BM morphological diagnosis, including cytochemistry, the immunophenotyping (IPT), and cytogenetics of each case, were collected and analyzed.
| Results|| |
A total of 138 infants underwent BM study between January 2010 and April 2015, out of which 38 cases were diagnosed as AL (27.5%). The mean age at presentation was 10.2 months. The youngest patient was 4 days old. The male–female ratio was 0.65:1 (15:23).
The presenting features of infantile AL cases are summarized in [Table 1]. Most of the infants presented with symptoms like fever (89.5%), failure to thrive (21.1%), abdominal distension (18.4%), and bleeding (7.9%). Pallor (86.8) was the most common sign. Hepatosplenomegaly was seen in 76.3%, lymphadenopathy in 47.4%, renomegaly in 7.9%, and petechiae in 5.2% cases. Central nervous system (CNS) involvement was seen in one case of ALL. None of the cases had mediastinal or testicular involvement. The mean lactate dehydrogenase (LDH) level was 1355.8 U/L [Table 1]
Based on PBS and BM morphology, supplemented by myeloperoxidase (MPO) and periodic acid Schiff (PAS) cytochemistry, the cases were classified as ALL [26 (68.5%)] and AML [12 (31.5%)]. Hyperleukocytosis (total white cell count >50 × 109/mm3) was seen in 13 cases − 10 cases of ALL and three cases of AML.
Immunophenotypic features: IPT conducted in 21 out of 26 cases of ALL confirmed precursor B ALL (CD19, 22, 79a, TdT positive) in 18 (85.7%) cases and precursor T ALL (CD3, 7, TdT positive) in three (14.3%) cases. CD34 was positive in 13 (61.9%) cases. Twelve (57.1%) cases of B ALL showed CD10 expression. Aberrant CD13 (myeloid antigen) expression was seen in one (4.8%) case of precursor B ALL.
IPT was conducted in 10 out of 12 cases of AML. CD13 and CD33 were positive in all cases. The cases were categorized as AML with minimal differentiation (M0) − three cases [MPO–CD13, 33 positive], AML without/with maturation (AML M1/2) − two cases [MPO, CD34, 13, 33 positive], acute monoblastic leukemia (M5) − three cases [CD64+, MPO−], acute megakaryoblastic leukemia (M7) − one case [CD61+, MPO−], and acute promyelocytic leukemia (APL) − one case [MPO+, HLA DR−]. Aberrant CD7 positivity was seen in two cases of AML M0 [Figure 1].
|Figure 1: Photomicrographs of cases of A. ALL B. AML M5 C. AML M 7 (TAM) D. APL|
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Cytogenetic features: karyotyping was done on metaphase preparations in 34 (23 ALL and 11 AML) cases. Recurrent genetic abnormalities observed included 1 case each of t(8;21)(q22,q22), t(15;17)(q22,q12), t(1;22)(p13,q13), and inv(3)(q21,q26) in AML. Mixed lineage leukemia (MLL) abnormalities [three cases (13.04%)] were observed in ALL, including two cases of t(4;11) and one case of additional chromosome 11q23. Trisomy 21 was seen in two cases of AML. However, both cases did not have clinical features of Down’s syndrome. Normal karyotype was seen in seven cases (26.9%) of ALL and one case (8.3%) of AML [Table 2].
|Table 2: Cytogenetic abnormality inAacute lymphoblastic leukemia and B acute myeloid leukemia|
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| Discussion|| |
Leukemia is the most common childhood cancer in India constituting 25 to 40% of all childhood cancers, displaying a rising trend. In a recent large Indian study of 266 cases of infantile malignancies, leukemias (25.19%) were the most common malignancies in contrast to Western literature where neuroblastoma is most common. The annual incidence of ALL (20 per million) in the United States is almost twice the rate of AML (10.6 per million). A total of 2.5 to 5% of pediatric ALL and 6 to 14% of pediatric AML occur in infants. The present study included 26 (68.5%) ALL and 12 (32.5%) AML cases.
Infant leukemias offer unique investigative models for the study of leukemogenesis. Complex interplay between inherited predisposition and exogenous exposures to agents with leukemogenic potential is involved. Familial clustering is not seen in the infant leukemias. Maternal consumption of alcohol; DNA topoisomerase-II-inhibitor-containing foods, such as fruits and vegetables that contain quercetin; soybeans (genistein); tea, cocoa, and wine (catechins); and caffeine have been related to infant AML. Exposure of the fetus to dipyrone, and mosquitocidals during pregnancy may cause MLL gene fusions. Infant leukemias have been associated with Down syndrome, Turner syndrome, and trisomy 9.
In the present study, both ALL and AML occurred more frequently in female than in male infants, which correlated with findings of Howlader et al.,
Acute lymphoblastic leukemia
ALL of infancy is associated with a high leukocyte count at presentation, hepatosplenomegaly, and CNS involvement. The immunophenotype is usually that of immature B-lineage precursors and is characterized by a lack of CD10 expression and the coexpression of myeloid-associated antigens. The frequency of MLL gene rearrangements is very high (75%). The primitive nature of leukemic cells in infants may partly account for their greater resistance to therapy.,, Mature B-ALL (Burkitt leukemia) is reported exceptionally and T-lineage ALL is found in only 4% of infant cases.
In the present study, out of 26 cases of ALL studied, only 7.7% of cases were under 6 months of age in contrast to other studies.,,,,,, ALL patients between 0 and 6 months of age at diagnosis as compared to older infants (6–12 months) show a more immature Ig/TCR pattern with greater prevalence of MLL abnormalities. The hemogram revealed a total leukocyte count (TLC) more than 100 × 109/mm3 in six (23.1%) cases, comparable with Silverman et al. (39%) and Dordelmann et al. (43%) [Table 3].
In the present study, 12 (57.1%) out of 18 cases of precursor B ALL were CD10 positive, which was comparable with the results of Silverman et al. [Figure 2]. CD10 positivity and absence of aberrant myeloid antigen expression is generally associated with a favorable outcome. Precursor T ALL constituted only three (14.3%) cases, in contrast to the results of Rajalekshmy et al.
|Figure 2: Comparison of A. CD 10 expression B. MLL abnormalities in infant ALL,,,|
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Molecular analysis of infant ALL reveals chromosome abnormalities in about 70 to 90% of patients, mainly representing translocations involving the MLL gene on chromosome 11q23. Fifty different MLL partner genes have been identified, with a predominance in infant ALL of the AF4 gene in t(4;11)(q21;q23), followed by the ENL gene in t(11;19)(q23;p13) and the AF9 gene in t(9;11)(p22;q23). Detection of a rearranged MLL gene has frequently been associated with poor clinical outcome.,,,
In the present study, karyotyping was conducted in 23 out of 26 cases of ALL. It was unsatisfactory in 10 cases (43.47%). MLL abnormality was seen in three out of 23 (13.04%) cases of ALL, which is low compared to the reported 66% [Figure 2]. Molecular diagnostic studies like fluorescent in situ hybridisation (FISH) recommended for cases in which MLL abnormality is suspected, but not detected by conventional karyotyping.
Out of three cases showing MLL gene abnormalities, two (66.7%) cases had hyperleukocytosis. CD10 negativity was seen in two (66.7%) cases. Two (66.7%) cases in which IPT was done showed B ALL phenotype. CD34 positivity was seen in one (33.3%) case.
The frequency of hyperdiploidy >50 chromosomes, a favorable prognostic feature, is highest in cases of CD10 positive early pre-B ALL. However, no hyperdiploidy or hypodiploidy were noted in the present study.
Acute myeloid leukemia
Remarkable progress has been made in the treatment of pediatric AML over the past few decades, and the overall probability of survival in newly diagnosed pediatric AML is now above 60%. Improvements may come from improved risk-group stratification, based either on novel genetic abnormalities, or on the monitoring of minimal residual disease. However, the factors that influence outcome in infants with AML remain obscure.
In the present study, 12 cases of infant AML were included. Hemogram revealed hyperleukocytosis in three cases. Age, gender, and hyperleukocytosis have not been proved to be significant prognostic variables in infant AML., An extramedullary (scalp) lesion was found in one case. No case of CNS involvement was noted.
IPT was done in 10 cases. Three (25%) of cases were categorized as AML M5, which was significantly lower than the available literature. Three (25%) of AML M0 cases were reported, which is higher than the results of Japan infant leukemia group and Creutzig et al., [Figure 2].
Cytogenetics is the most important prognostic factor in AML. Patients are classified into the following three risk categories: favorable, intermediate, and unfavorable. AML with t(15; 17)(q22; q12), t(8; 21)(q22;q22), and inv(16) are assigned to the favorable group. The prognosis of AML associated with 11q23/MLL or trisomy 8 remains controversial, and these cases are classified as intermediate or unfavorable according to study groups. On the other hand, it is usually considered that the complex karyotypes have the worst prognosis.
The frequency of 11q23 rearrangements in patients with AML decreases appreciably with age: they are detected in 43 to 58% of infants aged 12 months or less. MLL/11q23 rearrangements lacked prognostic significance in three studies, but were associated with a trend toward a worse outcome in one study. In the present study, MLL abnormality was not seen in AML cases.
One case each of t(15;17), t (8;21), and inv(3) were seen, with corresponding French American British (FAB) category, APL, AML M2, and AML M1, respectively. Inv(3), which is found in 2% of adult leukemias, is extremely rare in children and have so far never been detected in a patient with de novo AML younger than 12 years. In contrast, t(15;17) and t(8;21), the two most common reciprocal translocations in both adults and older children with AML, are very rare in infants aged less than 12 months. t(15;17) reported in a series of latino infants (11% of all AML cases) have been found to be associated with maternal agricultural chemical exposure t(1;22), a translocation resulting in the OTT–MAL gene fusion and highly correlated with acute megakaryoblastic leukemia, has been detected exclusively in children, 96% of whom were younger than 24 months. In the present study, t(1;22) was seen in a case of AML M0 with associated trisomy 21 and a complex kayotype (trisomies of chromosomes 4, 6, 7, 12, 18, 19).
A peculiar finding was the occurence of hyperdiploidy, which was seen in 5(45.5%) cases, out of which 3(27.3%) had no associated structural abnormalities. This is higher than the available literature (<1%). Although all chromosomes may be involved, extra copies of chromosomes 8 (68%), 21 (47%), 19 (37%), 13 and 14 (34% each), 10 (29%), and 4 and 11 (26% each) are the most common.
In the present study, trisomy 8 was seen in one (9.03%) case, trisomy 21 in two (18.1%) cases, trisomy 19 (36.3%) in four cases, and trisomy 18 in two cases (18.1%). Trisomy 8 was associated with complex karyotype in one case. Prognosis in trisomy 8 depends on whether it occurs as an isolated abnormality or is accompanying other aberrations; with complex karyotypes it is associated with poor prognosis. Complex karyotypes were seen in three cases. These are associated with unfavorable prognosis.
Transient myeloproliferative disease of the newborn is seen usually in association with Down’s syndrome. Spontaneous resolution of all blood and BM abnormalities occurs within 3 months of onset. In the present study, a 4-day-old neonate presented with fever and persistent crying. Peripheral smear revealed a TC higher than 100 × 109/mm3 with 90% blasts. IPT showed that these blasts were positive for CD61 and negative for CD34, MPO, CD13, and 33, consistent with AML M7. There were no features of Down’s syndrome. The baby was followed up for 4 months, during which spontaneous resolution of symptoms as well as normalization of total count and disappearance of blasts were noted. A retrospective diagnosis of transient abnormal myelopoiesis was made. Close follow-up was advised, but the case was lost for follow-up.
| Conclusion|| |
This study of the diverse phenotypic and genotypic features of infantile AL attempts to understand its biological behavior, which is essential in planning its effective management.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]