In TRPS1-negative cases, additional immunostains should be performed: CDX2 and SATB2 for colonic secondary EMPD; p63, GATA3 and uroplakin II/III for urothelial secondary EMPD; and PSA and NKX3.1 for prostatic secondary EMPD. The gene discussed is TRPS1; the disease is extramammary Paget disease.