title: CD7+ TdT+ chronic myelogenous leukemia blast crisis with null genotype.
abstract: Chronic myelogenous leukemia (CML) commonly evolves into blast crisis (BC). The blasts are usually of myeloid phenotype (70%), and less commonly of B-lymphoid phenotype (30%). Only rare reports of T lymphoblastic phenotype, and even fewer documented cases of T lymphoblastic genotype, are found. We report a case of Philadelphia (Ph) chromosome containing CML that evolved into a CD7+, TdT+, CD4-, CD8-, CD34-, HLA- DR+, blast crisis. The BC cells contained the Ph chromosome and expressed fusion bcr-abl RNA by polymerase chain reaction analysis, but had germline configuration of the T-cell receptor genes beta and delta, as well as germline configuration of immunoglobulin genes for heavy chain and kappa and lambda light chains. This case of CD7+ TdT+ leukemia thus represents either an early T-cell or true stem cell BC of CML, and demonstrates the need for gene rearrangement studies in T-cell phenotype BC.
authors.affiliation: Department of Internal Medicine, Wayne State University, Detroit, MI 48201-1998.
authors.forename: M R
authors.initials: MR
authors.lastname: Smith
authors.forename: A N
authors.initials: AN
authors.lastname: Mohamed
authors.forename: C
authors.initials: C
authors.lastname: Karanes
mesh_terms: D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000032:analysis*; D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte / Q000032:analysis*; D001752:Blast Crisis / Q000235:genetics* / Q000473:pathology; D004253:DNA Nucleotidylexotransferase / Q000032:analysis*; D015329:Gene Rearrangement, T-Lymphocyte; D005838:Genotype; D006801:Humans; D016130:Immunophenotyping; D007621:Karyotyping; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010641:Phenotype
chemical_list: D015703:Antigens, CD; D019011:Antigens, CD7; D000945:Antigens, Differentiation, T-Lymphocyte; D004253:DNA Nucleotidylexotransferase