Retrospective molecular screening reveals Leishmania (Leishmania) infantum in samples from patients investigated for suspected hematological neoplasms.

The coexistence of hematological neoplasms and Human Visceral Leishmaniasis (HVL) in the same patient may delay appropriate therapeutic intervention due to overlapping clinical and laboratory features. This highlights the need for careful differential diagnosis between these diseases, particularly in endemic regions where they may present similar clinical manifestations. The present study conducted a retrospective analysis of 112 clinical samples collected between 2011 and 2022, from patients referred to assigned suspected hematological neoplasms. Peripheral blood and bone marrow samples were analyzed by flow cytometry immunophenotyping using an extensive panel of monoclonal antibodies. Eighty-three samples were classified according to World Health Organization criteria as specific types of hematologic neoplasms, whereas 29 showed no evidence of neoplasia based on immunophenotypic evaluation using the applied antibody panel. The samples were subsequently analyzed by molecular methods for HVL, including touchdown PCR targeting kDNA and species-level confirmation by ITS1 amplification and sequencing. Leishmania (Leishmania) infantum was detected in a subset of samples, including one sample classified as a hematological neoplasm and three samples not classified as a hematological neoplasm. The evidence from this study indicates that samples initially investigated for hematological neoplasms may, in fact, be associated with or occur concomitantly with HVL. In endemic settings, the incorporation of sensitive molecular tools into the routine diagnostic workflow may improve etiological clarification, reducing the risk of misclassification and, consequently, inappropriate therapeutic management.