title: Non-neoplastic TdT-positive cells in bone marrow trephines with acute myeloid leukaemia before and after treatment express myeloid molecules.
abstract: OBJECTIVE
  Terminal deoxynucleotidyltransferase (TdT)-positive cells in non-neoplastic bone marrow are regarded as haematogones and show a characteristic morphology and immunophenotype. During our routine bone marrow trephine analysis of patients with acute myeloid leukaemia (AML) before and after treatment, we observed the presence of TdT-positive cells lacking CD34, CD10 and B cell antigens.
  
  
  METHODS
  To verify the nature of these TdT-positive cells, we analyzed 140 paraffin-embedded and decalcified trephines from 67 AML patients before and after therapy using double immunolabellings.
  
  
  RESULTS
  In 61% of the cases TdT-positive cells were present. After exclusion of neoplastic cells and haematogones, we identified that 16% of the cases harboured cells co-expressing myeloperoxidase and TdT, 15% glycophorin C and TdT, 13% CD117 and TdT and one case CD3 and TdT. These cells made up to 30% of the non-neoplastic TdT-positive cells. No differences in the number of TdT-positive cells before and after chemotherapy or stem cell transplantation could be observed.
  
  
  CONCLUSIONS
  While the reason of TdT expression by non-neoplastic myeloid cells is unknown, their presence should be taken into account when evaluating such cases.
authors.affiliation: Institute of Pathology, Charité - Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany. korinna.joehrens@charite.de
authors.forename: Korinna
authors.initials: K
authors.lastname: Jöhrens
authors.forename: Aylin
authors.initials: A
authors.lastname: Franke
authors.forename: Manfred
authors.initials: M
authors.lastname: Dietel
authors.forename: Ioannis
authors.initials: I
authors.lastname: Anagnostopoulos
mesh_terms: D000328:Adult; D000368:Aged; D015703:Antigens, CD / Q000378:metabolism; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000378:metabolism; D001706:Biopsy; D001853:Bone Marrow / Q000378:metabolism*; D019070:Cell Lineage; D004253:DNA Nucleotidylexotransferase / Q000378:metabolism*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D015470:Leukemia, Myeloid, Acute / Q000378:metabolism* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013234:Stem Cells; D055815:Young Adult
chemical_list: D015703:Antigens, CD; D014408:Biomarkers, Tumor; D004253:DNA Nucleotidylexotransferase