KLK3 and pachyonychia congenita: The prostate-specific antigen density (PSAD) has become a commonly used biomarker to enhance the accuracy of PSA.3 The PSAD threshold of 0.15 ng/mL/cc, particularly in cases of high PSA levels and negative multiparametric magnetic resonance imaging (mpMRI) results, has been suggested by Prostate Imaging Reporting and Data Systems (PI-RADS) version (v) 2.1 for the biopsy decision.4,5 Recent studies underlined that PSAD was a more accurate predictor of PC, having similar or better sensitivity but greater specificity compared to PSA levels.6-8