TdT Panel


Terminal deoxynucleotidyl Transferase

  • Tech Only CPT
  • Tech Pro CPT 88184, 88187, 88185x1
  • PowerPath Code FL TDT
  • Schedule Monday - Friday (Weekends by arrangement for clinically urgent Flow diagnostics)
  • Turn Around Time 1 Day
  • Disease State Lymphoblastic Leukemia
  • Methodology Flow Cytometry

Specimen Requirements

Bone Marrow or Peripheral Blood in Heparin or EDTA. Tissue in RPMI or sterile container with saline solution. Body Fluids in RPMI or sterile container
Bone Marrow or Peripheral Blood: 1.0 - 5.0mL - Tissue: 1cm (greatest dimension) in 2mL of RPMI - Body Fluids: 1.0 - 5.0mL

Clinical Significance

Acute B Lymphoblastic Leukemic cells are often distinguished from normal lymphocyte populations by a decrease in CD45 staining intensity. Sometimes CD45 is absent. Terminal deoxynucleotidyl Transferase (TdT), a specialized DNA polymerase expressed in immature lymphoma cells, is used also in this panel. For B-ALL, CD19, CD10, HLA-DR and TdT are often positive. Variability in staining can be seen on CD20, CD22, CD34 and CD45. Aberrant myeloid antigen expression most common includes CD13 and/or CD33.For T-ALL, CD7, CD45 and TdT are often positive. Variability in staining can be seen on CD2, CD3, CD5, CD10, and CD34. There may be dual positive or negative staining for CD4/CD8.

Required Patient Info

1) Requisition form with the patient’s name, DOB, DOC and recent treatments.
2) CBC report for Peripheral Blood.

Storage and Transportation

Bone Marrow and Peripheral Blood: 48-72hrs, transport at room temperature.
Tissue and Body Fluids: 24hrs, transport refrigerated.

Cause for Rejection

Specimens without 2 (two) patient identifiers. Incorrect anticoagulant or lack of anticoagulant, frozen or incorrectly stored specimens (i.e. excessive heat or cold), severely hemolyzed specimens (minimal hemolysis will be evaluated on a case-by-case basis), broken or leaking tubes, specimens received with needles affixed, submitted in fixative - no fixative is acceptable!, specimen age: >72 hours for peripheral blood and >5 days for bone marrow *see note below, clotted specimens (small clots are acceptable-others evaluated on a case-by-case basis), contamination (bacterial, fungal, drug interaction, chylous, etc.), incorrectly labeled specimens or insufficient transport media for tissues and FNA’s.

*Note: Peripheral blood specimens >72-hours old are reported on a case-by-case basis and must be approved by the pathologist reviewing the case.
Bone marrow specimens >5-days old are reported on a case-by-base basis and must be approved by the pathologist reviewing the case.


1 week


These tests were developed and the performance characteristics determined by CellNetix Pathology & Laboratories. They have not been cleared or approved by the US Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. This laboratory is certified under CLIA-88 and is qualified to perform high complexity clinical testing. Prognostic and predictive testing should be interpreted in the context of additional clinical and/or histopathological findings.