The analysis of karyotype tests in oncohematological patients is essential for the correct classification of the disease. One of the challenges in Brazil is conducting karyotype tests on transported samples due to the impact on cell viability, which can hinder accurate neoplasm classification.

To evaluate the performance of cytogenetic tests in a remote oncohematology laboratory for processing samples with suspected acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) received from 36 different medical centers and hospitals in Brazil and processed at NTO in São Paulo. Additionally, to assess the cell growth index and sensitivity for clone identification in AML and MDS.

Bone marrow samples from 203 patients at diagnosis, collected between January and June 2024, were analyzed. Neoplasm identification and classification were performed using 13-color immunophenotyping on the DXFlex flow cytometer (Beckman Coulter). The immunophenotyping results triggered reflex bone marrow karyotype testing in all samples, which were processed according to established protocols. The mean age was 64 years (1 to 92). For mitotic index classification in the karyotype test, cultures with 3 to 17 metaphases were classified as BIM (low mitotic index), fewer than 3 metaphases as ATM (absence of metaphases), and more than 18 metaphases as IMA (adequate mitotic index).

Of the 203 samples received and cultured after transportation from the collection center (up to 48 hours after collection), 140 (89.9%) were classified in the karyotype test as IMA (> 18 metaphases analyzed), 48 (23.6%) as BIM (3 to 17 metaphases), and only 15 (7.4%) showed no cell growth and were classified as ATM. Among those classified as IMA and BIM, 55 (39%) and 15 (31%) presented relevant cytogenetic alterations, respectively (chi-square p = 0.320). Thus, 93% of the samples processed for the laboratory diagnosis of AML or MDS were properly classified using immunophenotyping and cytogenetics. The most frequent alterations were deletions of chromosomes 5, 7, and 20, and the addition of chromosome 8.

Performing cytogenetic tests for the correct classification of AML or MDS is crucial at the beginning of the investigation. Successfully obtaining a cytogenetic result, even in samples with BIM, drastically contributes to clinical and therapeutic management. The comparative analysis of cytogenetic findings in samples with IMA or BIM was comparable (p = 0.320), and the ATM rate of 7.4% is lower than described in the literature, especially for samples sent to reference laboratories.

The protocols used for the laboratory diagnosis of AML or MDS in samples received from different medical centers in Brazil provided correct classification in 93% of the cases analyzed at diagnosis.