[Mucinous adenocarcinoma of the prostate. A case report and analysis of the literature].

An 80-year-old man, who had been treated for colon cancer 25 years ago, presented with gross hematuria. Rectal examination revealed a soft nodule in the right lobe. The serum prostatic specific antigen (PSA) was elevated to 5.2 ng/ml, while prostatic acid phosphate (PAP) was normal. Transrectal ultrasound revealed a hypoechoic mass in peripheral zone of the prostate and dilated seminal vesicle. A needle biopsy of the prostate showed mucinous adenocarcinoma. Under the diagnosis of prostatic tumor with seminal vesicle involvement, radical prostatectomy was performed. Histological findings showed organ confined cancer, of which most was composed of extracellular mucin lakes. Immunohistochemical study revealed the tumor cells positive for PSA and PAP. Mucinous adenocarcinoma of the prostate has been known to be clinically different from non-mucinous adenocarcinoma, in that the former is insensitive to hormonal therapy, is rarely associated with elevated PAP and rarely metastasize to the bone. But our analysis of the literatures is Japan showed no significant difference clinically between mucinous and non mucinous prostatic adenocarcinoma. However mucinous adenocarcinoma with signet ring cell rarely responds to hormonal therapy, which should not be classified to true mucinous adenocarcinoma in the current criteria. True mucinous adenocarcinoma could be a variant of prostatic adenocarcinoma, which is peripheral origin and should be treated like non-mucinous adenocarcinoma.