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  • Detection of terminal deoxynucleotidyl transferase (TdT) in nonhematopoietic small round cell tumors of children.

Detection of terminal deoxynucleotidyl transferase (TdT) in nonhematopoietic small round cell tumors of children.

Pediatric pathology & laboratory medicine : journal of the Society for Pediatric Pathology, affiliated with the International Paediatric Pathology Association (1997-11-14)
R C Mathewson, C R Kjeldsberg, S L Perkins
ABSTRACT

In the differential diagnosis of small round cell tumors (SRCTs), terminal deoxynucleotidyl transferase (TdT) is often used as a marker for lymphoblastic lymphomas and leukemias. However, the specificity of TdT using the avidin-biotin-immunoperoxidase (ABC) method is not well documented. To address this issue, we stained paraffin-embedded biopsy specimens of 64 cases of childhood SRCTs using the ABC method with anti-TdT. For any TdT-positive tumors, an additional antibody panel for lymphoid markers was applied. Two patterns of TdT positivity were observed: (1) tumor specific, consisting of strong to moderate nuclear staining, and (2) scattered positive lymphoid cells, usually in a perivascular location and expressing T-cell markers. Analysis showed that 7 of 10 medulloblastomas stained with TdT in a tumor-specific pattern (4 cases moderately to strongly positive in 75-100% of tumor cells, 3 cases weakly to moderately positive in 25-50% of cells). Also, 1 of 19 rhabdomyosarcomas and 1 of 8 Ewing's sarcomas showed moderate to strong tumor-specific TdT staining in 100 and 10% of cells, respectively. Scattered TdT-positive lymphoid cells were observed in 27% of these 64 SRCTs. These findings emphasize that TdT positivity should not be relied upon exclusively for making a diagnosis of lymphoblastic leukemia or lymphoma or ruling out other SRCTs.

MATERIALS
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Product Description

Sigma-Aldrich
TdT Rabbit Polyclonal Antibody