[Sclerosing adenosis of the prostate. Carcinoma simulation].

Sclerosing adenosis of the prostate is a benign lesion, which was not recognized until a few years ago. As in sclerosing adenosis of the breast, a background of various hyperplastic changes is commonly also present in the prostate. An incidence of 2.8% was reported in one series of resected hyperplastic prostatic glands. As demonstrated in this case report, the main problem lies in the differential diagnosis between sclerosing adenosis and highly differentiated adenocarcinoma of the prostate. Histological diagnosis of sclerosing adenosis based on routine HE sections is supplemented by immunohistochemical methods. Important diagnostic criteria of sclerosing adenosis are the presence of basal cell differentiation, which is demonstrated by cytokeratin 903, and signs of possible myoepithelial differentiation, with expression of S-100 and/or smooth muscle actin. These antibody expressions are lacking with in the presence of adenocarcinoma of the prostate. Nevertheless, in a small number of cases this differential diagnosis remains impossible, even after the application of immunohistochemical methods. Further studies are needed to shed some light on the relations between sclerosing adenosis, atypical adenomatous hyperplasia and adenocarcinoma of the prostate. So far, there appears to be no evidence of a direct relationship between sclerosing adenosis of the prostate and an elevated risk of carcinoma.