title: Novel CD19 expression in a peripheral T cell lymphoma: A flow cytometry case report with morphologic correlation.
abstract: BACKGROUND
  Peripheral T-cell lymphomas are uncommon lymphomas that show T-cell antigenic loss and clonal T-cell receptor (TCR) gene rearrangement. Rare cases of T-cell lymphomas with aberrant expression of CD20 have been described. However, CD19 coexpression in a mature T-cell neoplasm has not been reported.
  
  
  METHODS
  Histology, immunohistochemistry (IHC), and PCR for TCR gene rearrangement were performed on an excised lymph node specimen and a subsequent fine needle aspiration (FNA) of an additional lymph node. Flow cytometry (FC) was performed on FNA and peripheral blood specimen.
  
  
  RESULTS
  The lymph node's architecture was effaced by a diffuse atypical lymphoid proliferation that, by IHC, was positive for CD3, CD2, and CD43 and negative for CD4, CD5, CD8, TdT, CD1a, and B-cell-associated antigens PAX-5, CD20, and CD79a. A clonal TCR gene rearrangement was detected. FC was performed on a subsequent FNA, and peripheral blood specimen demonstrated an aberrant T-cell population with expression of CD2, CD3, CD27, TCR alpha/beta, CD52, CD38, CD45, and CD26 (partial expression) and negative for CD4, CD5, CD7, CD8, CD10, CD30, and CD56. The aberrant T-cell population also expressed bright CD19.
  
  
  CONCLUSIONS
  Using FC, we describe the first case of peripheral T-cell lymphoma with aberrant coexpression of CD19.
authors.affiliation: Flow Cytometry Unit, Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Rizzo
authors.forename: Maryalice
authors.initials: M
authors.lastname: Stetler-Stevenson
authors.forename: Wyndham
authors.initials: W
authors.lastname: Wilson
authors.forename: Constance M
authors.initials: CM
authors.lastname: Yuan
mesh_terms: D000328:Adult; D018941:Antigens, CD19 / Q000032:analysis* / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology*; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D003937:Diagnosis, Differential; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D016130:Immunophenotyping / Q000379:methods; D008198:Lymph Nodes / Q000276:immunology / Q000473:pathology; D016411:Lymphoma, T-Cell, Peripheral / Q000175:diagnosis* / Q000276:immunology* / Q000503:physiopathology; D008297:Male; D011237:Predictive Value of Tests; D013601:T-Lymphocytes / Q000276:immunology* / Q000473:pathology
chemical_list: D018941:Antigens, CD19; D015415:Biomarkers