Diagnostic Performance of the EuroFlow Acute Leukemia Orientation Tube (ALOT) in Pediatric Acute Leukemia: A Single-Center Experience

Background: Multiparameter flow cytometry is widely used in the diagnosis of acute leukemia, allowing for rapid identification of leukemic cells based on their immunophenotype. The EuroFlow Acute Leukemia Orientation Tube was designed as a standardized screening tool to support early diagnostic orientation and guide further, more targeted testing. In this study, we assessed the diagnostic performance of the ALOT panel in pediatric patients with suspected acute leukemia. Methods: A total of 254 pediatric patients (0–18 years) with suspected acute leukemia were analyzed. Bone marrow samples were assessed using multiparameter flow cytometry with the EuroFlow ALOT panel, comprising eight markers (MPO, cyCD79a, CD34, CD19, CD3, cyCD3, CD7, and CD45). Final diagnoses were established using extended immunophenotypic panels and additional diagnostic methods when required. Samples were processed according to EuroFlow standard operating procedures and acquired on FACSCanto II and FACSCanto 10-color flow cytometers (BD Biosciences). Diagnostic performance was assessed by calculating sensitivity, specificity, precision, accuracy, and negative predictive value. Results: Among 254 patients, 234 were diagnosed with hematologic disorders, while 20 had normal bone marrow findings. The ALOT panel correctly identified all pathological samples and did not misclassify any normal sample, resulting in 100% sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for discrimination between abnormal and normal samples. In terms of exact diagnostic orientation, ALOT correctly classified 244 of 254 cases (96.1%) using a single-tube approach. The remaining 10 cases (3.9%), including rare entities such as Burkitt leukemia, chronic myeloid leukemia, and transient myeloproliferative syndrome, required extended immunophenotypic evaluation. Importantly, these cases were not false negative results, as all were correctly identified as abnormal. Conclusions: The EuroFlow ALOT panel is a reliable screening tool for rapid diagnostic orientation in pediatric acute leukemia. Its implementation facilitates targeted selection of extended immunophenotypic panels, improving the efficiency and cost-effectiveness of diagnostic workflows.