Immunophenotyping in diagnosing pediatric acute leukemia after setting up the first flow cytometry unit in Mosul City in Iraq: an observational study of the project performed through a contribution from Japan.

Background: Flow cytometry (FCM) is a powerful tool for classifying acute leukemia (AL) to acute lymphoblastic leukemia (ALL) or acute myeloid leukemia (AML) and further subtyping. Accurate diagnosis of AL improves the outcome. Mosul, a city in Iraq, had no FCM laboratory yet, mainly due to repeated wars in the area. The Japan Chernobyl Foundation (JCF), a Japanese non-profit humanitarian organization, helped establish the first FCM Laboratory in Mosul. We aimed to evaluate the project from a scholarly point of view with a focus on childhood ALL.

Methods: An observational study was done after JCF provided the BD FACSCanto II system and all related materials. Anonymous data of the patients, including age, sex, address, initial complete blood count (CBC) with bone marrow aspirate (BMA) results, and coded FCM reports, were prospectively collected from February 2021 to January 2024. In addition to clinical notes on pediatric ALL cases, their treatment, and outcomes with a median follow-up of 26.2 (range, 0-44.3) months.

Results: Childhood ALL cases were 76, including (60, 78.9%) B-lineage ALL (B-ALL) and (16, 21.1%) T-lineage ALL (T-ALL) cases. B-ALL cases were classified as pro-B, common-B, pre-B, and mature-B, with frequencies of 11.7%, 76.7%, 10.0%, and 1.6%, respectively. T-ALL included early T-cell precursor (ETP), pro-T, pre-T, cortical-T, and medullary-T, with frequencies of 6.25%, 18.75%, 18.75%, 31.25%, and 25.00%, respectively. Furthermore, 20 pediatric AML cases were identified and sub-typed. Among ALL cases, the male-to-female ratio (M/F) was 1.5. There were 24 (31.6%) cases with white blood cell (WBC) counts of ≥50×10⁹/L and 29 (38.2%) who were aged ≥10 years or ≤12 months. There was a substantial association between high WBC and male sex with the T-ALL subtype. Based on clinical criteria and immunophenotyping of ALL, 47 (61.8%) of patients were identified as a high-risk (HR) group, while 29 (38.2%) were of standard-risk (SR) group. Relapses were reported in 8 (11.6%) patients with ALL, principally in the HR group. The induction mortality rate was 4.2%. Septic death was the leading cause of death (8/17, 47.1%), especially in those younger than 2 years old. The overall survival (OS) in ALL cases was 73.7%. The OS and event-free survival (EFS) for the SR group of ALL were 86.2% and 82.8%, respectively.

Conclusions: JCF's role was crucial in providing Mosul City, Iraq, with the first FCM Unit. The project made a breakthrough in AL diagnosis and established one of the important and supposed routine steps represented by ALL immunophenotyping. The HR group represented a significantly large portion of our ALL cases. Although the outcome was satisfactory for the SR group, the survival rate for the HR group was dismal. Further efforts are needed to scale up diagnostic and therapeutic capabilities to improve the outcome of ALL in Mosul City.