CD4+ CD56+ hematodermic neoplasm and plasmacytoid dendritic cell tumor: case report and review of the literature.

CD4+ CD56+ hematodermic neoplasm (HN) is a rare and aggressive neoplasm that has raised controversy regarding its etiology. CD4+ CD56+ HN is thought to be derived from plasmacytoid dendritic cells (pDCs) and most commonly stains with CD4, CD56, CD123, and T-cell leukemia/lymphoma 1 (TCL1). Skin manifestations usually are the presenting signs and vary in appearance. Lymph node involvement also is common at the time of presentation, and the natural course of the disease is a progression to leukemia. Treatment of CD4+CD56+ HN focuses on multiple chemotherapeutic regimens but none have been proven to successfully impact overall survival.