title: CD4+ CD56+ lineage negative malignancies: a new entity developed from malignant early plasmacytoid dendritic cells.
abstract: OBJECTIVE
  The CD4+ CD56+ lin- immunophenotype characterizes rare malignancies, so far considered as arising from the transformation of NK progenitors, and therefore classified as blastic NK-cell leukemia/lymphoma by the WHO committee. Recently it was formally demonstrated that such malignancies do, in fact, develop from plasmacytoid dendritic cells (pDC), according to immunophenotypic and functional criteria. The clinico-biological features of this neoplasm were moreover recently summarized from a large series of 23 patients.
  
  
  METHODS
  The main symptoms at presentation were cutaneous lesions and bone marrow failure, due to invasion by blastic cells, all of which were EBV negative and agranular. Most patients were initially sensitive to chemotherapy regimens, but they rapidly relapsed and died within 3 years. Only 2 allotransplanted patients were long survivors. Recurrent chromosomal aberrations involving chromosomes 5q, 6q, 12p, 13q, 15q and 9 were described and it was characteristic that these were associated in the same cell. In the present review we compared these findings to those in the literature.
  
  
  CONCLUSIONS
  The concordant characteristics led us to confirm that this neoplasm actually represents a new entity, that we propose to rename early pDC leukemia/lymphoma. The diagnosis is primarily based on a characteristic immunophenotypic profile i.e. CD4+ CD56+ CD3- CD13- CD33- CD19-. Complementary analyses assessing the expression of more specific pDC-related markers showed the cells to be HLA-DR+, CD123high, CD116low, CD45RA+, BDCA-2+ or BDCA-4+. Such complementary investigations are necessary only in the case of an atypical phenotype, in order to confirm a pDC origin and exclude another hematologic disease. This presently regards the expression of CD33 or cytoplasmic CD3e (cyCD3e) and the negativity of CD56.
authors.affiliation: EFS Rhône-Alpes, Dept. of Cellular Immunology, Grenoble, France. marie-christine.jacob@efs.sante.fr
authors.forename: Marie Christine
authors.initials: MC
authors.lastname: Jacob
authors.forename: Laurence
authors.initials: L
authors.lastname: Chaperot
authors.forename: Pascal
authors.initials: P
authors.lastname: Mossuz
authors.forename: Jean
authors.initials: J
authors.lastname: Feuillard
authors.forename: Françoise
authors.initials: F
authors.lastname: Valensi
authors.forename: Dominique
authors.initials: D
authors.lastname: Leroux
authors.forename: Marie-Christine
authors.initials: MC
authors.lastname: Béné
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Bensa
authors.forename: Francine
authors.initials: F
authors.lastname: Brière
authors.forename: Joël
authors.initials: J
authors.lastname: Plumas
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015704:CD4 Antigens / Q000096:biosynthesis*; D019002:CD56 Antigen / Q000096:biosynthesis*; D002648:Child; D003713:Dendritic Cells / Q000737:chemistry / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D007938:Leukemia / Q000175:diagnosis / Q000209:etiology* / Q000473:pathology*; D008297:Male; D008875:Middle Aged
chemical_list: D015704:CD4 Antigens; D019002:CD56 Antigen