Cutaneous Manifestation of a Rare Haematological Malignancy: A Case Report of the Presentation, Diagnosis, and Management of Blastic Plasmacytoid Dendritic Cell Neoplasm.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematological malignancy characterized by the proliferation of abnormal plasmacytoid dendritic cells. These cells infiltrate the skin and other organs during malignancy, leading to the development of violaceous skin nodules. We report a case of a middle-aged patient who presented to a secondary hospital with persistent skin lesions unresolved by primary care management and corticosteroids. A surgical excision and biopsy in secondary care revealed malignant plasmacytoid activity diffusely positive for Cluster of Differentiation (CD)4, CD123 and CD56 alongside a high Ki-67 proliferation index.  A hyperfractionated cyclophosphamide, vincristine sulfate, doxorubicin hydrochloride (Adriamycin), and dexamethasone (Hyper-CVAD) chemotherapy regimen was initiated for this patient, which resulted in a significant reduction in lesion size and an initial remission. Central nervous system (CNS) prophylaxis with intrathecal methotrexate was provided following chemotherapy to prevent CNS relapse while awaiting allogenic bone marrow transplantation.  This case highlights the importance of considering BPDCN in patients with persistent or unusual skin lesions and highlights the critical role of early biopsy and immunohistochemistry in achieving an accurate diagnosis. Moreover, it emphasizes the need for a multidisciplinary team (MDT) approach to ensure optimal management and improve prognosis and patient care with this malignancy.