Concurrent Adenoid Cystic/Basal Cell Carcinoma and Acinar Adenocarcinoma of the Prostate: Comprehensive Molecular Analysis of Both Tumor Component.

Adenoid cystic/basal cell carcinoma (ACBCC) of the prostate is a rare tumor, with only about 100 tumors reported in the literature. We present a 66-year-old man with incidental finding of prostatic cancer duplicity-ACBCC of the prostate and prostatic acinar adenocarcinoma in radical prostatectomy specimen. Prostatic acinar adenocarcinoma was of Gleason score 6 (3 + 3), focally present at surgical margin, exhibited perineural invasion but no extraprostatic extension. Concurrently, ACBCC was detected, the tumor exhibited adenoid cystic-like morphology, with multifocal involvement of the resection margins and extraprostatic extension. This coincidence presented a unique opportunity to comprehensively examine the molecular characteristics of both tumors. SETD2 mutation was identified in ACBCC, while it was absent in acinar adenocarcinoma. No significant differences were detected by other genetic analyses, and both tumors clustered together within "Prostatic adenocarcinoma" control group and separated from adenoid cystic carcinoma of other locations using methylation profiling.