Immunophenotype of Acute Lymphoblastic Leukemia: The Experience of University Hospital Centre Casablanca - Morocco

Acute lymphoblastic leukemia (ALL) encompasses a group of lymphoid neoplasms that morphologically and immunophenotypically resemble B-lineage and T-lineage precursor cells. Our objective is to describe the immunophenotypic aspects of acute lymphoblastic leukemia (All) diagnosed by flow cytometry at the hematology laboratory of IBN ROCHD University Hospital Center and to compare them with those reported in other series.

This is a descriptive study over a period from August 2016 to October 2021, during a 5 year-and-2-month period. Immunophenotyping was performed at the flow cytometry unit on a Beckman-Coulter with 6 colors and 2 lasers in the hematology laboratory of the same hospital and data was collected retrospectively from the patients' files, their medical prescription files, kalisil software, and a data collection form we have established.

The 440 patients had ages ranging from 1 month to 76 years, with a median of 9.5 years and the overall male-to-female ratio was 1.44. The immunological subtyping revealed that 82.5% of cases were B-ALL and 17.5% were T-ALL; of these B-ALL cases 230 (63.36%) were children (range: 0.1 - 15 years) and 134 (36.91%) were adults (range: 16 - 76 years); T-ALL were distributed in both age groups, 49 cases (37.7%) were children (range: 2 - 15 years) and 28 (21.56%) were adults (range: 18 - 63 years). All patients presented at least one abnormal blood count; thrombocytopenia has been observed in 89.4% of cases, anemia in 86.5% of cases, hyperleukocytosis in 79.8% of cases, leukopenia in 10.6% of cases, and pancytopenia in 4.8% of cases. The frequency of B-cell markers in B-ALL was found to be 363 (100%) for CD19, 323 (88.94%) for CD10, 290 (80%) for CD79a, and 73 (20%) for CD20. CD34 expression was found in 73 (20%) cases of B-ALL. HLA-DR was found in 54 (15%) cases, while TdT was found in 43 (13%) cases. Aberrant expression of myeloid antigens was found in 94 (26%) cases of B-ALL. Among T-ALL, the positivity of CD3 and CD7 was 100% (77 cases), while CD5 was positive in 58 (75%) cases. CD34 expression was found in only 19 cases of T-ALL. CD4 and CD8 expression was checked in only 9 adult patients and 4 pediatric cases. Out of them, 77.82% of cases were negative for both CD4 and CD8. CD4 and CD8 double positivity was seen in only 11.1% of cases, and 22.4% of cases showed either CD4 or CD8 positivity.

We concluded that our study was similar to reports in the Americas and Europe, and it was the first large one that describes the immunophenotypic profile of ALL in the Moroccan population.