Her-2 expression in cutaneous eccrine and apocrine neoplasms.

Area of Science:

• Dermatopathology
• Oncology
• Molecular Pathology

Background:

• Cutaneous adnexal glands share similarities with breast tissue, complicating differentiation between primary skin neoplasms and metastatic breast carcinoma.
• Human Epidermal growth factor Receptor 2 (HER-2) protein is overexpressed in 10-34% of breast carcinomas.
• HER-2 expression in cutaneous neoplasms is not well-characterized, necessitating investigation for diagnostic utility.

Purpose of the Study:

• To determine HER-2 protein expression in benign and malignant cutaneous eccrine and apocrine neoplasms.
• To assess the value of HER-2 expression in distinguishing primary cutaneous lesions from metastatic breast carcinoma.

Main Methods:

• Retrieved 85 primary cutaneous neoplasms and 11 cutaneous metastases from HER-2-positive breast carcinomas.
• Evaluated HER-2 protein expression using the Dako Hercept Test kit.
• Analyzed membranous HER-2 staining patterns.

Main Results:

• HER-2 protein expression was observed in 3.5% (3/85) of cutaneous adnexal neoplasms (one hidrocystoma, two nodular hidradenomas).
• Seven of 11 (63.6%) cutaneous metastases from HER-2-positive breast carcinomas retained moderate-to-strong HER-2 expression.
• A significant difference in HER-2 expression was noted between primary cutaneous neoplasms and metastatic breast lesions.

Conclusions:

• The low rate of HER-2 overexpression in cutaneous adnexal neoplasms suggests distinct nosological entities compared to breast carcinomas.
• HER-2 protein expression serves as a valuable marker for differentiating primary cutaneous appendageal neoplasms from HER-2-expressing metastatic breast carcinoma.
• This diagnostic tool aids in accurate clinical management and treatment strategies for patients with cutaneous lesions.