Fortunately, the question of the use of immunohistochemistry for the differential diagnosis of urothelial and prostatic adenocarcinoma has been addressed in detail, including with best practices recommendations promulgated by ISUP [62,63]; urothelial carcinoma frequently expresses p63, HMWCK, CK5/6, GATA3, and CK7, along with Uroplakins, which are all negative in prostatic luminal neoplasms excepting rare prostatic adenocarcinomas with aberrant p63 expression [87,88]. The gene discussed is GATA3; the disease is urothelial carcinoma.