Abstract

Benign and malignant neoplasms of sweat glands and breast may be morphologically as well as immunophenotypically similar. A recent study showed that trichorhinophalangeal syndrome type 1 (TRPS1) immunohistochemical stain is a highly sensitive and specific marker for breast carcinoma. In this study, we analyzed TRPS1 expression in a spectrum of cutaneous sweat gland tumors. We stained 5 microcystic adnexal carcinomas (MACs), 10 eccrine carcinomas, 1 hidradenocarcinoma, 5 porocarcinomas, 11 hidradenomas, 9 poromas, 7 cylindromas, 3 spiradenomas, and 10 syringomas with TRPS1 antibody. All of the MACs (5/5) and syringomas (10/10) were negative. Every cylindroma (7/7) and 2 out of 3 spiradenomas demonstrated intense staining in cells lining ductular spaces with negative to relatively weak expression in surrounding cells. Out of 16 cases from the remaining malignant entities, 13 were intermediate to high positive, 1 was low positive, and 2 were negative. A total of 20 hidradenomas and poromas revealed intermediate to high positivity in 14 cases, low positivity in 3 cases, and 3 cases with negative staining. Our study demonstrates a very high (86%) expression of TRPS1 in malignant and benign adnexal tumors that are mainly composed of islands or nodules with polygonal cells, e.g. hidradenoma. On the other hand, tumors with small ducts or strands of cells, such as MAC and syringoma, appear to be completely negative. This differential staining among types of sweat gland tumors may represent either differential cells of origin or divergent differentiation and has the potential to be used as a diagnostic tool in the future. Further studies with larger case groups are needed for better classification of this variable expression profile.

Financial Disclosure:
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