Date of Award

7-30-2010

Document Type

Dissertation

Degree Name

Master of Medicine (MMed)

First Supervisor/Advisor

Riyat Malkit

Second Supervisor/Advisor

William M Macharia

Third Supervisor/Advisor

Ritesh Pamnani

Department

Pathology (East Africa)

Abstract

Background: Reliable distinction between AML and ALL is important for the selection of appropriate therapy. The final diagnosis of acute leukemia should be based on clinico-pathological, morphological, cytochemical and molecular cytogenetics data, together with immunophenotypic information. Flow cytometry has become the preferred method for the lineage assignment and maturational analysis of malignant cells in acute leukemias. Immunophenotyping has also allowed the detection of aberrant antigen co expression and the analysis of heterogeneity and clonality of malignant cells in acute leukemias. It is insufficient to merely make a diagnosis of acute leukemia, or even AML or ALL. Further classification is essential in order to determine the prognosis and select the most appropriate treatment. Furthermore, immunophenotypic characteristics of acute leukemias have not been described in Kenya yet and the existing immunophenotypic patterns of the disease in Nairobi are not known.

Objective: The main objective was to determine the relative frequencies of Acute Leukemia immunophenotypes using commonly expressed markers and to describe clinicopathological characteristics.

Setting: The study was carried out at Aga Khan University Hospital Laboratory between March 2009 and March 2010.

Patients and methods: One hundred and thirty two consecutive blood and bone marrow specimens were analyzed for cytomorphological characteristics and immunophenotypic markers. The clinical-pathological characteristics were also recorded for each patient with acute leukemia. The immunological category was assigned using the EGIL criteria. The end point was the immunophenotypic profiles and the association of each immunophenotype with the clinical and pathological features. Immunophenotyping was done by Flow cytometry.

Results: There were 132 patients in total in whom immunophenotyping was done. These comprised of 67(50.8%) males and 65(49.2%) females with M: F ratio of 1.03:1. The age ranged from 2 years to 87 years with a median age of 29.5 years. There were 88 cases of AML and 42 cases of ALL. Only 2 cases of biphenotypic leukemia were studied. AML was found to occur more in adults with a total of 76 (86.4%) cases in patients above 15 years of age and only 12 (13.6%) cases in those below 15 years of age. The commonest AML immunophenotype in all patients was AML-M2 accounting for 26 (29.5%) cases with 19 (21.5%) cases seen in adults and 7(7.95%) in children. The peak adult age range for AML patients was 41-50 years. The proportion of AML-M4 in this study was 19.3%.

Majority of ALL cases were B-ALL phenotype at 29 (96.6%) with the dominance of early pre-B phenotype at 62.07%, followed by Common B- ALL in 37.93%.There were 4 cases of T-ALL one of which was seen in a patient below 15 years. The phenotype associated with most cases of adenopathy was the Pre B-cell ALL but this was not statistically significant (P=0.193). The majority of patients presented with anaemia with the median hemoglobin of 7.45g/dl (range 2-15g/dl). The median platelet count level was 55.1 (range 4-462 X109/L).

Conclusion: The relative frequencies of the immunological subtypes in this study are similar to those reported by developed countries in the world, except for the low frequency of T-ALL and absence of AML-M6 and AML-M7. Results concerning the antigen expression compares well with what has been reported in other studies in developed and developing countries.

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