P504S can be used as a positive marker for PIN. It will be useful to. confirm the diagnosis of small focus of prostate carcinoma in needle biopsies. The combination of P504S + HMW CKs + p63 (PIN-4â¢ Cocktail) may be extremely. useful for diagnosing prostatic intraepithelial neoplasia, especially in difficult cases, and in cases with limited tissues.