Shah RB, et al. - Researchers aimed to determine the clinical significance of “atypical intraductal proliferation” (AIP) when present in needle biopsy (NBX) without IDC-P (intraductal carcinoma of the prostate). Over 7 years, AIP was diagnosed in 62 NBX cases, with estimated incidence of 1%. Subsequent biopsy diagnosis of: benign prostate (2), IDC-P with PCa (1), and PCa (3) was received by 6 of the 12 AIP only patients. In 93% of patients with AIP and GG1 or GG2 PCa, defined as: GG >3 (15%), IDC-P (77%), cribriform Gleason pattern 4 (69%), pT3a (77%), or pT3b (8%), they detected the presence of one or more adverse pathologic features at subsequent radical prostatectomy. In suspected low to intermediate risk PCa, unsampled IDC-P and/or other adverse pathologic characteristics may be indicated by AIP in NBX. They recommended taking into account AIP as a distinct entity from high-grade prostate intraepithelial neoplasia for risk assessment and, additionally, it warrants consideration for further work-up to detect unsampled high risk PCa.