Are certain high grade prostatic intraepithelial neoplasia subtypes associated with increased risk of prostatic adenocarcinoma?

Background: High grade prostatic intraepithelial neoplasia (PIN) is a presumed precursor lesion of prostatic adenocarcinoma (PCa). Studies have shown that extensive sampling of prostatic tissue and multifocal PIN are better predictors of cancer than unifocal PIN diagnosed on limited samples. However, currently there is no consensus on overall management and subsequent follow-up of PIN. Moreover, to the best of our knowledge, there are only a few studies on the morphologic patterns of PIN to stratify men with an increased risk of PCa. Thus, we aimed to study the correlation of the morphologic patterns of PIN with the subsequent progression to PCa. Design: We reviewed 323 patients who underwent transrectal needle biopsies and diagnosed with isolated PIN without current or prior diagnosis of carcinoma or atypical glands at our institution from 2009 to 2016. The following parameters were recorded: 1. Morphologic pattern of PIN which were divided into 4 categories with increasing complexity - flat, tufted, micropapillary and cribriform. When more than one pattern was present the more complex pattern was assigned. 2. Extent of PIN: Focal (1 core); multifocal (\u3e1 to 3 cores) and extensive (\u3e 3 cores). Results: Out of 323 patients, 7 patients were re-categorized as being negative for PIN and were excluded from final analysis. The distribution of the pattern and extent of PIN in the remaining 316 cases is provided in Table 1 & 2 respectively. No cancer was seen in cases with flat PIN, 10% of cases with tufted morphology progressed to PCa, 18% of cases with micropapillary morphology progressed to PCa and 25% of cases with cribriform morphology progressed to PCa. Out of 9 cases with micropapillary morphology, 4 cases were multifocal, 3 cases were extensive and 2 cases showed focal involvement. When only multifocal or extensive involvement was noted, 25% of the cases with micropapillary morphology progressed to PCa. Our data suggest that morphologic patterns of PIN are associated with progression to PCa (χ2 =17.850; df=3;