Mucinous adenocarcinoma of urinary bladder type, arising from prostatic urethra in a patient treated with radiotherapy for acinar type prostatic adenocarcinoma: a case report

Abstract

We present here a case of mucinous adenocarcinoma of urinary bladder type, arising from the prostatic urethra in a 78-year-old man who also had a previous history of prostatic adenocarcinoma of acinar type treated with radiotherapy. The patient presented to the clinic with haematuria. A biopsy from the prostatic urethra showed poorly differentiated mucinous adenocarcinoma favouring primary mucinous urothelial adenocarcinoma. The subsequent transurethral resection of prostate revealed poorly differentiated (signet-ring) malignant cells floating in pools of extracellular mucin within the prostatic stroma. The overlying urothelium exhibited intestinal metaplasia and glandular dysplasia. The tumour was positive for cytokeratin 20, villin, CEA and CDX2 but was negative for prostate specific antigen (PSA), Alpha methylacyl co-A racemase (AMACR) and cytokeratin 7. Beta catenin showed positive membrane staining. Mucinous adenocar-cinoma arising from the prostatic urethra is a rare and aggressive tumour which must be differentiated from prostatic mucinous adenocarcinoma, metastatic colonic adenocarcinoma and meta-static adenocarcinoma from urinary bladder. These tumours share morphological and immunohistochemical features with enteric adenocarcinoma, and the presence of surface intestinal metaplasia and glandular dysplasia in this case favours a urothelial origin.