الفهرس 
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Abstract
Acute leukemia is heterogeneous group of hematological malignancies characterized by clonal expansion of immature myeloid or lymphoid precursors (blasts). Acute leukemia is the most common form of cancer in children, comprises approximately 30 percent of all childhood malignancies.
The accurate assignment of patients to stratified risk groups can be a difficult, expensive and slow process, requiring intensive laboratory studies including morphology, cytochemistry, immunophenotyping and cytogenetic diagnostics. One of the most important laboratory features used to categorize leukemia cases is the presence of specific chromosomal aberrations that in many cases determine therapy and at diagnosis is believed to be the most powerful prognostic factor in acute leukemia.
The gold standard for cytogenetic investigation is still conventional cytogenetics over the years; methods of cytogenetic analysis evolved and became a part of routine laboratory testing. The reference material for cytogenetic investigation is obtained during bone marrow aspiration. Peripheral blood cells are used only if bone marrow cells are unavailable.
The aim of the present work is to study the cytogenetic aberrations present in acute leukemia in children to clarify the diagnosis, indicate prognosis, assist the choice of a treatment strategy and support further research.
The study was conducted on 20 newly diagnosed acute leukemia patients with age ranging between 6 months to 12 years, who were diagnosed at the Hematology Oncology Unit at Alexandria University, Children’s Hospital, El Shatby.
The patients were subjected to the following tests:
1. Detailed history taking.
2. Complete physical examination.
3. laboratory investigations: Complete blood picture include Hb% and RBCs count, WBCs total and differential, Platelet count and examination of blood film for detection of blasts, bone marrow aspiration and immunophenotyping of B.M blasts.
4. Cytogenetic analysis using conventional cytogenetic technique on bone marrow and peripheral blood if bone marrow was not available and >10% circulating blasts were present.
The results of the present study were as follows:
• Patients were classified to two groups, fifteen ALL patients and five AML patients.
• High frequency of patients (65%) was found among 1- <10 years age group.
• The median age for ALL patients was 4 years, ranging from 6 months to 12 years, while that of AML patients, the median age was 3 years ranging from 9 months to 10 years.
• Male to female ratio was 1.14:1 in ALL compared to 1.5:1 in AML with overall male preponderance in both types of leukemia.
• Positive history of tobacco exposure was detected among patients.
• The frequency of ALL was more prominent than AML, 15 patients were diagnosed with ALL (75%) and 5 were diagnosed with AML (25%), 93.3% of ALL patients were B-ALL and 6.7% were T-ALL.
• The most common FAB subtype in ALL was L1 with (66.7%) and M0 for AML with (40%).
• The most common symptom for ALL and AML was fatigue (93.3% & 80%) followed by fever (73.3% & 40%) and weight loss (20%) for each. The most common sign for ALL and AML was pallor (86.8% & 80%) followed by hepatomegaly (60% & 40%) and lymhadenopathy (46.6% & 40%), respectively.
• Anemia was seen in almost all ALL and AML patients, Leukocytosis in (53.4% & 40%) and thrombocytopenia in (73.3% & 80%) of the patients, respectively.
• The median bone marrow blasts at the time of diagnosis in ALL was (82%) with minimum (25%) and maximum (98%) and for AML patients, the median was (66%) with minimum (22%) and maximum (80%).
• A complete remission without relapse or partial response was achieved in 8 ALL patients (53.3%) and 3 AML patients (60%).
• Clinical and hematological parameters in ALL patients in relation to prognosis showed better remission rates in 1 - <10 years age group, female sex, hepatomegaly, lymphadenopathy, Hb <11gm/dl,WBCs count >50.000/mm3 , platelets > 150,000/mm3 and L1 FAB type (60%, 57.2%, 66.7%, 57.2%, 53.8% ,62.5% 75% and 60%, respectively).
• Clinical and hematological parameters in AML patients in relation to prognosis showed better remission rates in 1 - <10 years age group, male sex, Hb <11gm/dl, WBCs count<50.000/mm3 and platelets> 150.000/mm3. Poor treatment responses were present in AML patients with hepatomegal and lymphadenopathy and M0 FAB type.(66.7%, 66.7%, 60%, 66.7%,100%,100% and 100%, respectively)
• Cytogenetic analysis couldn’t be performed in 4 patients (16.6%), yielded no metaphases on bone marrow samples and had <10% blasts in peripheral blood and were excluded from the study.
• Normal karyotype was found in 2 ALL patients (13.3%).
• Cytogenetic abnormalities were found in 86.6% of ALL patients and 100% of AML patients.
• In ALL, numerical abnormalities was found in 7 patients (46.6%). hyperploidy was the commonest abnormality identified. Two patients had 47 chromosomes, with +15 and +21. hyperdiploidy (mn 47-57) and near triploidy (mn58-80) with clones of near tetraploidy(81-103) were found in 2 patients. Hypodiploidy were found in 3 patients, 2 had modal chromosome number of 45 with -13, -20 and 1 patient had near hypoploid (mn<34).
• In ALL, only structural abnormalities were found in 5 patients (33.3%). Deletion was the commonest structural abnormality seen in 4 patients in chromosomes 3p, 9p, 12p, 13q. One T-ALL patient had t(5;9)(q33;q22).
• In ALL, structural with numerical abnormalities was found in 1 patient (6.6%) with -5, -6 and -9 combined with del (6p).
• In AML, numerical abnormalities were detected in 1 patient (20%) with +19, Only structural abnormalities were found in 3 patients (60%). The main structural abnormalities were deletions within 2 patients. One had del (5q) with clones of del (6p) and the other had del (7p) with clones of del (8p). The last patient had t(8,21) with other clone of i(8q). Structural with numerical abnormalities (20%) were found in 1 patient with t(15;17) with other clones of + 8.
• ALL patients were classified into favourable (n=4; 26.7%) (hyperdiploidy, near triploidy with clones of near tetraploidy,+21 and del 12p), intermediate (n=2; 13.3%)(normal karyotype), adverse (n=5; 33.3%)(hypoploidy,del 6q, 9p, 13q and -13) and unknown cytogenetic risk groups (n=4; 26.7%)(+15, -20, del 3p and t(5;9).
• AML patients were classified into favourable (n=2; 40%)( t(8:21), t (15:17), )intermediate (n=0), adverse (n=2; 40%)(del 5q and 6p,7p and 8p) and unknown cytogenetic risk groups(n=1;20%)(+19)
• CR was achieved in ALL patients with favourable, intermediate, unfavourable and unknown cytogenetic risk in 100%, 100%, 0% and 50%, respectively and CR was achieved in AML patient with favourable, adverse and unknown cytogenetic risk in 100%, 0% and 100%, respectively.