title: CD4(+) CD56(+) lineage-negative malignancies are rare tumors of plasmacytoid dendritic cells.
abstract: CD4(+) CD56(+) lineage-negative malignancies are difficult to diagnose and classify. Recent studies have suggested that these malignancies may derive from plasmacytoid dendritic cells (pDC). In this report, we examine 10 cases of CD4+, CD56+ lineage-negative malignancies that presented in various tissue sites. The goal was to identify the morphologic, immunophenotypic, and genotypic findings to devise a diagnostic approach to tissue biopsies of these lesions and to confirm the proposed cell of origin. The mean age was 66 years (range, 45-80 years) with a male predominance (8 males/2 females). Frequent sites of disease included skin (60%) and peripheral blood/bone marrow (70%). Tumor cells were positive for CD45, CD43, CD4, and CD56 (9 of 10). The pDC markers, CD123 (9 of 10) and CD45RA (10 of 10), were detected by immunoperoxidase staining. Also noted was CD2 positivity (1 case), weak CD7 positivity (4 of 8 cases), weak CD33 (4 of 9 cases), TdT (2 cases), and CD68 (2 cases). All cases were otherwise negative for EBV (EBER), B-cell, T-cell, myeloid, and NK cell markers. T-cell receptor-gamma gene rearrangement was negative in all cases. Complex structural chromosomal abnormalities were seen in 3 of 5 cases, a subset of which may be recurrent in pDC malignancy. Overall prognosis was poor despite multiagent chemotherapy and/or radiation. Our study confirms that CD4+/CD56+ lineage-negative tumors are derived from pDC and have characteristic clinical, histopathologic, and immunophenotypic features. Furthermore, these rare neoplasms can be readily diagnosed using recently developed immunoperoxidase techniques.
authors.affiliation: Department of Pathology, University of New Mexico, 2325 Camino de Salud, Albuquerque, NM 87112, USA.
authors.forename: Kaaren K
authors.initials: KK
authors.lastname: Reichard
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Burks
authors.forename: M Kathryn
authors.initials: MK
authors.lastname: Foucar
authors.forename: Carla S
authors.initials: CS
authors.lastname: Wilson
authors.forename: David S
authors.initials: DS
authors.lastname: Viswanatha
authors.forename: John C
authors.initials: JC
authors.lastname: Hozier
authors.forename: Richard S
authors.initials: RS
authors.lastname: Larson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis*; D015704:CD4 Antigens / Q000378:metabolism*; D019002:CD56 Antigen / Q000378:metabolism*; D019070:Cell Lineage; D003713:Dendritic Cells / Q000473:pathology*; D005260:Female; D019337:Hematologic Neoplasms / Q000175:diagnosis* / Q000503:physiopathology*; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D014408:Biomarkers, Tumor; D015704:CD4 Antigens; D019002:CD56 Antigen