HER2 and EGFR expression in cutaneous spindle squamous cell carcinoma

Area of Science:

• Oncology
• Dermatopathology
• Molecular Biology

Background:

• Epidermal growth factor receptor (EGFR) and HER2 are transmembrane receptor tyrosine kinases (RTKs) involved in cell signaling and implicated in tumorigenesis.
• Approximately 80% of cutaneous squamous cell carcinomas (SCC) express EGFR, but expression in primary cutaneous spindle squamous cell carcinoma (SSC) is unstudied.
• RTK expression in extracutaneous spindle cell carcinomas is a prognostic indicator of potentially poor outcomes.

Purpose of the Study:

• To investigate the expression of EGFR and HER2 in primary cutaneous spindle squamous cell carcinoma (SSC).
• To evaluate the potential prognostic and therapeutic implications of EGFR and HER2 expression in SSC.

Main Methods:

• Retrieved 13 archival cases of primary nonmetastatic cutaneous SSC.
• Utilized immunohistochemistry to assess EGFR and HER2 expression.
• Confirmed all cases by a board-certified dermatopathologist prior to study.

Main Results:

• None of the 13 cases (0%) showed HER2 immunoreactivity.
• Only one case (<8%) demonstrated positive EGFR staining.
• EGFR and HER2 are not overexpressed in primary cutaneous SSC.

Conclusions:

• The lack of EGFR and HER2 overexpression in SSC supports the notion of its limited metastatic potential.
• Findings suggest variability in EGFR and HER2 expression among SCC histologic subtypes.
• This variability may have significant prognostic and therapeutic implications for SSC management.