FREQUENCY AND LOCATION OF MITOSES IN PROSTATIC INTRAEPITHELIAL NEOPLASIA (PIN)

The aim of our study was to assess the frequency and location of mitos es in routine haematoxylin- and eosin-stained sections of prostatic in traepithelial neoplasia (PIN) and then to compare the patterns with th ose in benign prostatic hyperplasia (BPH) and prostatic invasive adeno carcinoma (PAC). The frequency of mitoses in the epithelial cell layer s increased from BPH through PIN lip to PAC. The proportions of mitose s in PIN lesions of low grade (PINlow) and high grade (PINhigh) were g reater than in BPH (mean 0.001%; standard error; SE, 0.001%), the valu es decreasing from the basal layer towards the lumenal. In PINlow, the mean category values were 0.087% (SE 0.04%) in the basal, 0.046% (SE 0.033%) in the intermediate and 0.024% (SE 0.024%) in the lumenal posi tion. In PINhigh, the mean category values were 0.194% (SE 0.178%) in the basal position, 0.075% (SE 0.06%) in the intermediate and 0.049% ( SE 0.033%) in the lumenal position. The proportions of mitoses in aden ocarcinoma with cribriform pattern decreased from the basal towards th e lumenal layer, as for PIN: 0.154% (SE 0.096%) in the basal position, 0.072% (SE 0.044%) in the intermediate and 0.064% (SE 0.04%) in the l umenal position. In the solid/trabecular adenocarcinomas, the mean cat egory value in the cell layer adjacent to the stroma was 0.22% (SE 0.1 11%), whereas in the other cell layers it was 0.074% (SE 0.045%). In s mall and large acinar adenocarcinomas, the proportions of mitoses were 0.058% (SE 0.024%) and 0.068% (SE 0.019%), respectively. In conclusio n, the evaluation of mitotic frequency and location in haematoxylin- a nd eosin-stained sections gives ncaa ate information on how the mitoti c activity in PIN compares with BPH and PAC.