title: S-100A1 is a reliable marker in distinguishing nephrogenic adenoma from prostatic adenocarcinoma.
abstract: Nephrogenic adenoma is a benign lesion that may occur at any site of the genitourinary tract, usually in association with previous urothelial injuries. Although its pathogenesis is still debated, recent studies seem to confirm its derivation from renal tubular epithelium, rather than from a metaplastic process of urothelium. In addition to its uncertain origin, there can be diagnostic difficulty in distinguishing nephrogenic adenoma from prostatic adenocarcinoma, particularly with lesions arising in the prostatic urethra. So far, immunohistochemical stains are often needed to make such a distinction, and several markers have been proposed, often with controversial results. S100A1 is a calcium binding protein that has been recently reported to be expressed in renal tubular cells and in a subset of renal cell neoplasms. Alpha-methylacyl-CoA racemase (AMACR), a recently identified prostate cancer marker, has also been found to be expressed in renal tubules and in some renal epithelial neoplasms. In this study, we investigated the expression of S100A1 and AMACR in 18 nephrogenic adenomas and in 100 prostatic adenocarcinomas. A strong and distinct cytoplasmic or nucleocytoplasmic staining of S100A1 was found in 17 out of 18 cases of nephrogenic adenoma (94%), but never in prostatic adenocarcinoma. In contrast, AMACR expression was detected in 14 of 18 nephrogenic adenomas (78%) and in 96 of 100 prostatic adenocarcinomas (96%). We conclude that (1) S100A1 is a specific and sensitive immunohistochemical marker to differentiate nephrogenic adenoma from prostatic adenocarcinoma; (2) AMACR immunostaining does not seem to be a useful marker in distinguishing between these 2 lesions; (3) given that both S100A1 and AMACR have been reported to be expressed in renal tubular cells and in a subset of renal cell neoplasms, our findings confirm the histogenetic relationship between nephrogenic adenoma and renal tubular epithelium.
authors.affiliation: Department of Pathology, University of Sassari, Via G. Matteotti 58, Sassari, Italy. pcossurocca@yahoo.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Cossu-Rocca
authors.forename: Marcella
authors.initials: M
authors.lastname: Contini
authors.forename: Matteo
authors.initials: M
authors.lastname: Brunelli
authors.forename: Antonella
authors.initials: A
authors.lastname: Festa
authors.forename: Francesca
authors.initials: F
authors.lastname: Pili
authors.forename: Stefano
authors.initials: S
authors.lastname: Gobbo
authors.forename: Albino
authors.initials: A
authors.lastname: Eccher
authors.forename: Antonica
authors.initials: A
authors.lastname: Mura
authors.forename: Giovannino
authors.initials: G
authors.lastname: Massarelli
authors.forename: Guido
authors.initials: G
authors.lastname: Martignoni
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000378:metabolism; D000236:Adenoma / Q000175:diagnosis* / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000032:analysis; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D019998:Racemases and Epimerases / Q000096:biosynthesis; D009418:S100 Proteins / Q000096:biosynthesis*; D012680:Sensitivity and Specificity; D014565:Urogenital Neoplasms / Q000175:diagnosis* / Q000378:metabolism
chemical_list: D014408:Biomarkers, Tumor; D009418:S100 Proteins; C110294:S100A1 protein; D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase