Early T-cell precursor lymphoblastic leukemia accompanied by prominent blastic plasmacytoid dendritic cell proliferation mimicking blastic plasmacytoid dendritic cell neoplasm: an exceptional case report and literature review

Plasmacytoid dendritic cells (pDCs) are commonly associated with myeloid malignancies. The association between lymphoblastic leukemia and pDCs has been little explored.Here, we report a novel case of early T-cell precursor lymphoblastic leukemia (ETP-ALL) accompanied by prominent proliferation of blastic pDCs mimicking BPDCN. The diagnosis was established based on a comprehensive analysis of morphology, immunophenotype and clinical implications. We also present a literature review and discussion on the differential expression of reactive and neoplastic pDCs, the functional role of pDCs in lymphoblastic leukemia, and the etiological association of normal pDCs and BPDCN.The current case demonstrates for the first time that prominent pDC proliferation can be associated with lymphoid neoplasms and can exhibit blastic morphology and immunophenotype. The underlying mechanism of the coexistence of these two blastic populations remains unknown. Further genetic profiling may be required to denote the progressive development of tumor stem cells to the lymphoid, myeloid or dendritic cell lineage. Moreover, the prognostic value of pDCs in hematological neoplasms needs further investigation.