MUC5AC and prostate carcinoma: Although true mucinous or colloid prostatic adenocarcinoma, with extensive mucin production, remains a rare entity (Epstein and Lieberman, 1985; Nagakura et al, 1986), production of neutral mucin as assessed by immunohistochemistry is found in up to 55% of prostate carcinomas (Sentinelli, 1993).