Blastic plasmacytoid dendritic cell neoplasm without cutaneous lesion at presentation: case report and literature review.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and highly aggressive hematological malignancy derived from precursors of plasmacytoid dendritic cells. This disease typically presents with cutaneous involvement as the first manifestation, with subsequent or simultaneous spread to bone marrow and peripheral blood. It is exceedingly rare to diagnose BPDCN without a cutaneous lesion. Here, we report a 21-year-old male who was diagnosed with BPDCN in the absence of cutaneous symptoms. Clinically, left inguinal nodules were noticed for 4 months. The diagnosis of BPDCN was established based on histological and immunohistochemical study of a lymph node biopsy. The patient was classified as stage IVA with bone marrow involvement and underwent three cycles of hyper-CVAD alternating with high-dose methotrexate and cytarabine. A complete response was established after one cycle; however, the patient relapsed with disseminated cutaneous lesions and bone marrow involvement following a response duration of 10 months. This case is significant for BPDCN presenting with lymph node and bone marrow involvement in the absence of characteristic cutaneous manifestations.