Atypical Small Acinar Proliferation and High-grade Prostatic Intraepithelial Neoplasia in the Era of Multiparametric Magnetic Resonance Imaging: A Contemporary Review

Multiparametric magnetic resonance imaging (mpMRI) has added to the armamentarium for the diagnosis and surveillance for organ-confined prostate cancer. Atypical small acinar proliferation and high-grade prostatic intraepithelial neoplasia (HGPIN) are premalignant prostatic lesions. The management of such lesions remains contentious, and the addition of mpMRI introduces further uncertainty, given its ability to pick up indolent lesions and its use in targeted biopsy. We aimed to perform a comprehensive review of current evidence regarding atypical small acinar proliferation, high-grade prostatic intraepithelial neoplasia, and mpMRI to ascertain a consensus for a current management algorithm.