Trophoblast cell-surface antigen 2 evaluation in intraepithelial neoplasia and intraductal carcinoma of the prostate: An immunopathological study

The origin of intraductal carcinoma of the prostate (IDC-P) in presence of prostate adenocarcinoma (PCa) is a matter of debate. This study evaluates trophoblast cell-surface antigen 2 (Trop-2) expression in prostatic high-grade intraepithelial neoplasia (HGPIN), IDC-P and PCa to explain the possible mechanism for IDC-P arising. Trop-2 was localized in the luminal epithelium of normal prostate gland, HGPIN and IDC-P. The quantitative analysis of immunohistochemistry showed no difference of Trop-2 expression between HGPIN and IDC-P, while statistically significant differences were observed comparing the two pathologies with normal tissues. Contrarily, Trop-2 was expressed in 2.5% of the basal cells in normal prostate gland and in 1% of HGPIN while Trop-2 was expressed in 8% of cells in IDC-P samples. We suggest that Trop-2 present in the basal cells may acquire neoplastic changes. The neoplastic cells could grow into the glandular lumen as HGPIN and/or spread into the duct as IDC-P or spread into the stroma as PCa. In conclusion, our data in part support the theory of intraductal carcinoma origin through retrograde glandular colonization.