title: Immunohistochemical evaluation of TMPRSS2-ERG gene fusion in adenosis of the prostate.
abstract: Adenosis (atypical adenomatous hyperplasia) is a benign lesion that morphologically mimics prostate adenocarcinoma, although the relationship between these 2 lesions is still debated. The TMPRSS2-ERG fusion is a common chromosomal rearrangement that occurs early in the development of invasive adenocarcinoma of the prostate and results in the expression of a truncated ERG protein. This fusion is present in 50% of adenocarcinomas and in 20% of high-grade prostate intraepithelial lesions. Until recently, fluorescent in situ hybridization was the only method available to detect these rearrangements. A specific anti-ERG antibody is now available for detecting ERG protein expression and serves as a useful marker for ERG rearrangements. Formalin-fixed, paraffin-embedded tissue sections of adenosis from cases of prostate biopsies (n = 30), transurethral resections of the prostate (n = 12), and radical prostatectomies (n = 3) were analyzed via immunohistochemistry for ERG. None (0%) of the foci of adenosis were positive for ERG protein expression. Of 40 cases of Gleason score 6 adenocarcinoma on a tissue microarray, 22 (55%) were positive for ERG protein. Of the positive cases, 14 (63.6%) were moderate in intensity, with the remaining 36.4% being weak. The lack of ERG expression in adenosis supports the notion that it is not a precursor lesion of adenocarcinoma. Moreover, it suggests that immunohistochemistry for ERG expression could be a useful tool to differentiate adenosis from adenocarcinoma.
authors.affiliation: Department of Pathology, The Johns Hopkins Hospital, Baltimore, MD 21231, USA.
authors.forename: Whitney M
authors.initials: WM
authors.lastname: Green
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Hicks
authors.forename: Angela
authors.initials: A
authors.lastname: De Marzo
authors.forename: Peter P B
authors.initials: PP
authors.lastname: Illei
authors.forename: Jonathan I
authors.initials: JI
authors.lastname: Epstein
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism*; D004273:DNA, Neoplasm / Q000235:genetics; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D050596:Oncogene Fusion / Q000235:genetics*; D011230:Precancerous Conditions / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011468:Prostatectomy; D011470:Prostatic Hyperplasia / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D046888:Tissue Array Analysis; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D000071230:Transcriptional Regulator ERG
chemical_list: D004273:DNA, Neoplasm; C072312:ERG protein, human; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D012697:Serine Endopeptidases; C421305:TMPRSS2 protein, human
keywords: Adenocarcinoma; Adenosis; ERG; Prostate; TMPRSS2