Revealing Hidden Nodal Disease: FDG PET/CT Driven Detection of Occult Lymph Node Involvement in Blastic Plasmacytoid Dendritic Cell Neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive malignancy characterized by skin involvement and frequent systemic dissemination. We report a case of a 32-year-old man with multiple violaceous cutaneous nodules who underwent F-18 FDG PET/CT for staging. PET/CT demonstrated extensive metabolic activity in cutaneous sites and revealed previously unsuspected inguinal and cervical lymph-node involvement. Histopathology confirmed BPDCN. This case highlights the crucial role of FDG PET/CT in detecting subclinical nodal disease, delineating total disease burden, and improving staging accuracy in BPDCN, thereby supporting its value in guiding management and future response assessment.