TdT expression in normal and neoplastic sebaceous cells

Abstract

Aims

Terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase expressed in immature, normal and neoplastic, lymphoid or hematopoietic cells and in neuroendocrine carcinomas, like Merkel cell carcinoma and small cell carcinoma. It has not yet been described in cells of epithelial origin. After observing TdT immunoreactivity in normal sebaceous glands we analyzed its spectrum of expression in cases of sebaceous cell hyperplasia and sebaceous cell neoplasms.

Methods & Results

Twelve cases of sebaceous gland hyperplasia (SGH), and three cases of other benign lesions, namely, sebaceoma, sebaceous adenoma and sebaceous nevus, along with four archived cases of sebaceous cell carcinomas (SC) were collected and stained with TdT antibody. In addition, tissue microarrays (TMAs) were constructed from eleven cases of basal cell carcinoma (BCC) and ten cases of squamous cell carcinoma (SCC), which offered nine evaluable cases each, and after carcinoma type confirmation with immunostaining for epithelial membrane antigen (EMA), TdT immunohistochemistry was performed. All cases of SGH and sebaceous cell neoplasms were positive for TdT. Staining intensity was variable, often weak to moderate in a significant proportion of cells, apart from one case of SC and the case of sebaceous nevus that were only focally positive. None of BCC and only one SCC showed immunoreactivity.

Conclusions

TdT protein can be found in epithelial origin cells and specifically sebaceous cells, both benign and malignant. It can be hypothesized that this expression is due to sebaceous cell nature to be lead into apoptosis via its holocrine secretion mode. Additional studies are needed to further elucidate its biological role.

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