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Published on: February 7, 2019
Reactivity with TdT in Merkel cell carcinoma: a potential diagnostic pitfall
Cary J Buresh1, Bahram Robert Oliai, Rodney T Miller
1Immunohistochemistry Division, ProPath Laboratory, Dallas, TX 75247, USA.
American Journal of Clinical Pathology
|May 16, 2008
Summary
Terminal deoxynucleotidyl transferase (TdT) is present in 73% of Merkel cell carcinoma (MCC) cases. This finding highlights a potential diagnostic pitfall when differentiating MCC from lymphoblastic lymphoma.
Area of Science:
- Oncology
- Dermatopathology
- Immunohistochemistry
Background:
- Merkel cell carcinoma (MCC) is an aggressive skin neuroendocrine cancer.
- MCC shares cytomorphologic features with lymphoblastic lymphoma.
- Terminal deoxynucleotidyl transferase (TdT) is typically found in T-cells and certain leukemias.
Purpose of the Study:
- To investigate the expression spectrum of TdT in Merkel cell carcinoma.
- To assess the diagnostic implications of TdT reactivity in MCC.
Main Methods:
- Immunohistochemical analysis was performed on 26 MCC tumor samples.
- TdT immunoreactivity was evaluated in tumor cells.
Main Results:
- TdT was identified in 19 out of 26 (73%) MCC cases.
- TdT staining intensity varied but was often moderate to strong.
- TdT expression was observed in a significant proportion of MCC cells.
Conclusions:
- TdT expression in MCC can mimic lymphoblastic lymphoma.
- This reactivity may pose a diagnostic challenge, especially when CD45/CD20 are negative.
- Awareness of TdT expression in MCC is crucial for accurate differential diagnosis.
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