Psammomatous Calcifications Identified in Targeted Needle Biopsies and Radical Prostatectomy From IDH1 Mutant Prostatic Adenocarcinoma

IDH1 mutant prostatic adenocarcinoma represents a small fraction of prostate cancer with distinct epigenetic changes, characterized by genome-wide DNA hypermethylation. Recently, prostatic adenocarcinoma with intratumoral psammomatous calcifications was found to frequently harbors IDH1 R132 mutations. However, the association with IDH1 hotspot mutations and psammomatous calcifications in prostate cancer remains controversial. Here we report another rare case of IDH1 R132H mutant prostatic adenocarcinoma, showing intratumoral psammomatous calcifications identified in targeted needle biopsies as well as subsequent radical prostatectomy specimen. This case provides independent evidence for identification of IDH1 mutant prostate cancer by combined histologic features, including intratumoral psammomatous calcifications, anterior tumor location, and high Gleason score. In addition, to our knowledge, this is the first case of multifocal prostate cancer reported in the literature, with the co-existence of spatially disparate and genetically distinct tumor foci harboring IDH1 R132H mutation or TMPRSS2 - ERG gene fusion in the same prostate.