26508 Blastic plasmacytoid dendritic cell neoplasm

Abstract

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic neoplasm that arises from precursors of plasmacytoid dendritic cells. Clinical findings of BPDCN may be nondescript, making histologic evaluation, with the aid of immunohistochemical stains, essential. We present a case of a 76-year-old male with no known medical history who presented with chief complaint of a lesion on his chest. He previously thought the lesion was a bruise; however, when it failed to resolve, he sought medical evaluation. The patient denied personal or family history of hematologic malignancy. Thorough review of systems was negative with the exception of recent onset fatigue. Physical examination revealed a solitary, well-defined erythematous-to-violaceous plaque with a central nodular component on the patient’s chest. A 4-mm punch biopsy was obtained from the nodular component. Hematoxylin–eosin evaluation demonstrated dermal nodules of tumor cells extending into the fat with sparing of the overlying epidermis. Individual cells were oval in shape with dispersed nuclear chromatin and eccentric pink plasmacytoid-like cytoplasm. Immunohistochemistry staining was positive for CD123, CD56, and CD4, but negative for CD3, supporting a diagnosis of BPDCN. Subsequently, the patient was referred to hematology and oncology for systemic evaluation and treatment. Our case highlights a rare entity as well as underscores the importance of immunohistochemical stains in accurately diagnosing hematologic neoplasms with cutaneous manifestations. While rare, BPDCN represents an important diagnostic consideration for dermatologists as it most commonly presents in the integumentary system and early identification may impact treatment course and outcome.