CD4+/CD56+ haematodermic neoplasm: a preculsor haematological neoplasm that frequently first presents in the skin.

CD4+/CD56+ hematodermic neoplasm, formerly known as blastic NK cell lymphoma, is an aggressive and rare preculsor hematologic neoplasm recently recognized by the WHO-EORTC classification consensus for cutaneous lymphomas. The neoplasm tends to affect elderly patients, who usually present with skin lesions but often have a disseminated disease, including bone marrow involvement. Although the lesions are composed of cells with a lymphoblast-like morphology and an NK-cell phenotype, exhibiting a CD4+, CD56+ positive immunophenotype, recent studies support a relationship to plasmacytoid dendritic cells. Because of the rarity of this disease, we describe two patients suffering a CD4+/CD56+ hematodermic neoplasm.