Purpose: We investigated the association of MRI findings in men with a previous diagnosis of atypical small acinar proliferation (ASAP) or multifocal high-grade intraepithelial neoplasia (HGPIN) with pathologic findings on repeat biopsy.
Materials and methods: We retrospectively reviewed patients with ASAP/multifocal HGPIN undergoing a repeat biopsy in the Michigan Urological Surgery Improvement Collaborative registry. We included men with and without an MRI after the index biopsy demonstrating ASAP/multifocal HGPIN but before the repeat biopsy. Men with an MRI prior to the index biopsy were excluded. We compared the proportion of men with ≥ GG2 CaP (Grade Group 2 prostate cancer) on repeat biopsy among the following groups with the χ2 test: no MRI, PIRADS (Prostate Imaging-Reporting and Data System) ≥ 4, and PIRADS ≤ 3. Multivariable models were used to estimate the adjusted association between MRI findings and ≥ GG2 CaP on repeat biopsy.
Results: Among the 207 men with a previous diagnosis of ASAP/multifocal HGPIN that underwent a repeat biopsy, men with a PIRADS ≥ 4 lesion had a higher proportion of ≥ GG2 CaP (56%) compared with men without an MRI (12%, P < .001). A lower proportion of men with PIRADS ≤ 3 lesions had ≥ GG2 CaP (3.0%) compared with men without an MRI (12%, P = .13). In the adjusted model, men with a PIRADS 4 to 5 lesion had higher odds (OR: 11.4, P < .001) of ≥ GG2 CaP on repeat biopsy.
Conclusions: MRI is a valuable diagnostic tool to triage which men with a history of ASAP or multifocal HGPIN on initial biopsy should undergo or avoid repeat biopsy without missing clinically significant CaP.
Keywords: MRI; atypical small acinar proliferation; multifocal high-grade intraepithelial neoplasia.