Relapsing Blastic Plasmacytoid Dendritic Cell Neoplasm With Neurologic Involvement.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy characterized by cutaneous, bone marrow, and central nervous system (CNS) involvement. Despite advances in therapy, prognosis remains poor, particularly in relapsed or refractory disease. We present the case of a woman in her 30s with a history of BPDCN diagnosed three months prior at an outside hospital following symptoms of blurry vision, headaches, night sweats, and weight loss. She achieved initial remission after AML-type induction chemotherapy (7+3 with cytarabine and idarubicin) but was lost to follow-up and received no consolidation therapy. She re-presented with worsening B symptoms, multiple new violaceous skin lesions, diffuse bone pain, ocular involvement, and progressive neurologic deficits. Diagnostic evaluation confirmed widespread relapse with infiltration of skin, lymph nodes, bone marrow, orbit, CNS, and lungs. She was treated with intrathecal chemotherapy and systemic daunorubicin/vincristine but demonstrated refractory disease and developed diffuse alveolar hemorrhage with cytologic confirmation of pulmonary BPDCN involvement. Given the aggressive relapse and complications, she is being transitioned to targeted therapy with tagraxofusp, with plans for eventual allogeneic stem cell transplantation pending clinical stability. This case highlights the fulminant course of relapsed BPDCN in a young patient, the limitations of conventional chemotherapy, and the urgent need for early consideration of novel targeted therapies. Recognition of atypical manifestations, including ocular and pulmonary involvement, is essential to guide timely diagnosis and management.