Immunoreactivity for estrogen receptor protein in sweat gland tumors

The histologic and immunophenotypic similarities between sweat gland carcinoma and breast cancer are well known. Indeed, these likenesses often preclude the diagnostic separation of primary cutaneous glandular neoplasms from metastatic mammary carcinomas, based on light microscopic and immunohistochemical features alone. To assess whether the presence of estrogen receptor protein (ERP) in breast carcinoma might serve as a diagnostic marker in this context, we analyzed 33 eccrine carcinomas, 24 sebaceous carcinomas, 15 intraepidermal apocrine carcinomas (extramammary Paget's disease), and 42 benign sweat gland tumors for ERP content. The monoclonal anti-ERP H222 was used with a modified avidin-biotin-peroxidase complex (ABC) method and paraffin sections. For comparison, eight cutaneous metastases of mammary carcinomas were similarly studied. ERP was identified in six of eight secondary neoplasms. However, this steroid-binding protein also was detected in 10 of 33 eccrine carcinomas. In three of 10 eccrine hidradenomas, each of two examples of hidradenoma papilliferum, and two of three chondroid syringomas, ERP-reactivity was noted as well. The remaining eccrine, apocrine, and sebaceous neoplasms were nonreactive. Among immunoreactive eccrine neoplasms, eight of 10 carcinomas occurred in males, whereas most ERP-positive benign eccrine tumors arose in females. The potential expression of ERP by sudoriferous malignancies reinforces the biologic similarities between mammary and cutaneous adnexal neoplasms. Moreover, ERP reactivity in the latter lesions underscores the inability of immunohistochemistry to distinguish primary and secondary glandular tumors of the skin with certainty.