Impressive Skin and Systemic Response Despite Patient Underestimation and Delayed Diagnosis of Blastic Plasmacytoid Dendritic Cell Neoplasm.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy derived from precursors of plasmacytoid dendritic cells (pDCs), most frequently presenting with cutaneous involvement and often progressing to bone marrow (BM), lymph node, and central nervous system (CNS) infiltration. Owing to its heterogeneous and often indolent initial presentation, diagnosis is frequently delayed, potentially worsening prognosis. We report the case of a 55-year-old man with long-standing underrecognized cutaneous and nodal lesions that eventually evolved into disseminated BPDCN. The patient was successfully treated with intensive chemotherapy (CHT) using a hyper-CVAD regimen combined with intrathecal therapy (IT), achieving complete remission (CR). Consolidation with allogeneic hematopoietic stem cell transplantation (allo-HSCT) from a matched sibling donor resulted in sustained minimal residual disease (MRD)-negative CR. At 23 months post transplant, the patient remains disease-free with full donor chimerism and no evidence of graft-versus-host disease (GvHD). This case highlights the diagnostic challenges of BPDCN, the importance of early recognition of atypical cutaneous lesions, and supports the role of intensive CHT followed by allo-HSCT as an effective therapeutic strategy in eligible patients.