ERG expression in intraductal carcinoma of the prostate: comparison with adjacent invasive prostatic adenocarcinoma

Abstract

Intraductal carcinoma of the prostate is a growth pattern of prostatic adenocarcinoma that has not been well characterized from the molecular standpoint. It remains debatable whether intraductal carcinoma of the prostate represents colonization of benign glands by pre-existing conventional prostatic adenocarcinoma, or progression of high-grade prostatic intraepithelial neoplasia. TMPRSS2-ERG is the most common gene fusion in conventional prostatic adenocarcinoma, identified in about 40-70% of cases. In this study, we compared the expression of ERG in intraductal carcinoma of the prostate and adjacent conventional prostatic adenocarcinoma. Thirty-one confirmed cases of intraductal carcinoma of the prostate, with adjacent conventional prostatic adenocarcinoma and available tissue blocks, were identified at our institution. Immunohistochemical stains were performed for ERG using a rabbit anti-ERG monoclonal antibody. The ERG expression in the intraductal carcinoma of the prostate component was compared with that in the adjacent conventional prostatic adenocarcinoma. Mean patient age was 65 years (range: 48-79 years). Positive ERG expression was identified in 11/31 (35%) cases of intraductal carcinoma of the prostate. In all 11/11 (100%) cases with positive ERG expression in the intraductal carcinoma of the prostate component, ERG expression was also positive in the adjacent conventional prostatic adenocarcinoma. In the 20/31 cases with negative ERG expression in the intraductal carcinoma of the prostate component, ERG was also negative in the adjacent conventional prostatic adenocarcinoma. It is highly conceivable that based on the identical ERG expression (positive or negative) in intraductal carcinoma of the prostate and the adjacent conventional prostatic adenocarcinoma, intraductal carcinoma of the prostate most likely represents colonization of benign glands by adjacent pre-existing conventional prostatic adenocarcinoma.

Atypical Intraductal Cribriform Proliferations of the Prostate Exhibit Similar Molecular and Clinicopathologic Characteristics as Intraductal Carcinoma of the Prostate

“…They found identical ERG expression in IDC and the adjacent invasive carcinoma similar to our study and concluded that IDC most likely represented colonization of benign glands by adjacent preexisting invasive carcinoma. 21 In our current study, we found that the ERG status of all AIP foci were identical to the ERG status of the nearby invasive carcinoma similar to our previous observations. 8 This contrasted with the ERG status of HGPIN.…”

Molecular evidence that invasive adenocarcinoma can mimic prostatic intraepithelial neoplasia (PIN) and intraductal carcinoma through retrograde glandular colonization

“…IDC-P, for instance, has been suggested as a defined morphological entity that is associated with worse prognosis [48–50]. More recent cytogenetic and IHC studies suggested a clonal relationship with adjacent invasive prostate cancer based on ERG [42,59]. In the present study, a subset of cases for which clonality was addressed using TMPRSS2–ERG breakpoint analysis contained IDC-P.…”

ERG and FLI1 are useful immunohistochemical markers in phosphaturic mesenchymal tumors

“…This is because diagnostic usefulness of ERG has been revealed in prostate pathology especially dealing with intraductal neoplastic lesion [15]. Expression status of ERG in intraductal carcinoma of the prostate and its adjacent conventional adenocarcinoma was the same; it is thus supposed that intraductal carcinoma of the prostate is a lesion reflecting colonization of conventional adenocarcinoma in benign glands [16]. Another intraductal lesion, high-grade prostatic intraepithelial neoplasia, was similar to intraductal carcinoma of the prostate in morphology, but was not immunostained with ERG [15].…”