TRPS1 expression is sensitive and specific for primary extramammary Paget disease

Area of Science:

• Oncology
• Dermatopathology
• Biomarker Research

Background:

• Extramammary Paget disease (EMPD) is an epithelial neoplasm affecting the vulva and scrotum, characterized by neoplastic cells infiltrating squamous epithelium.
• Differential diagnosis includes melanoma in situ and secondary tumors, with current biomarkers like CK7 and GATA3 lacking specificity.
• Pagetoid spread can occur in various sites, including anorectal mucosa, complicating diagnosis.

Purpose of the Study:

• To evaluate the utility of TRPS1, a novel breast biomarker, in the diagnosis of pagetoid neoplasms.
• To assess TRPS1's sensitivity and specificity in distinguishing primary EMPD from other vulvar, scrotal, and anorectal neoplasms.
• To determine if TRPS1 can aid in excluding secondary involvement by other tumors.

Main Methods:

• Immunohistochemical analysis of TRPS1 expression in archival tissue samples.
• Evaluation of 15 primary EMPD cases from the vulva and 4 from the scrotum.
• Assessment of TRPS1 in differential diagnostic cases, including melanoma in situ, urothelial carcinoma, and anorectal adenocarcinomas with pagetoid spread.

Main Results:

• Strong nuclear TRPS1 immunoreactivity was observed in all primary EMPD cases (vulva and scrotum).
• Cases of vulvar melanoma in situ, secondary pagetoid spread of urothelial carcinoma, and anorectal adenocarcinomas were negative for TRPS1.
• Weak TRPS1 staining in non-neoplastic keratinocytes was less intense than in tumor cells.

Conclusions:

• TRPS1 is a sensitive and specific biomarker for diagnosing Extramammary Paget disease.
• TRPS1 is particularly useful in differentiating primary EMPD from secondary involvement by urothelial and anorectal carcinomas.
• The findings support TRPS1 as a valuable tool in the diagnostic workup of pagetoid neoplasms.