Tubulo-villous adenoma with severe dysplasia in the prostatic urethra: A case report and histogenetic considerations

In 2002, Seibel et al. presented a case series of 18 patients with villous adenomas of the urethra. Since then, only a couple of reports regarding this rare entity have been published. Recently (2013), Kao and Epstein proposed a new entity of tubular adenoma (4 cases) in the urinary tract, being similar to tubular adenomas in gastrointestinal (GI) tract; no following cases have been reported. Herein presented a case of tubule-villous adenoma (TVA) in the prostatic urethra (PU) of a 77-year-old man male patient suffering from dysuria. Cystscopy showed a polypoid/villous tumor of the PU, and transurethral resection of this tumor was performed. Grossly, fragments of the tumor measured 12 mm in diameter and polypoid/villous. Microscopically, it was a TVA indistinguishable from GI adenomas. No urothelium was seen, but a few normal prostatic glands were noted. The tumor showed mild to severe dysplasia, but in situ malignant transformation and invasive malignancy were not seen. Histochemically, acidic mucins were present. Immunohistochemical staining results of the tumor cells were as follows: cytokeratin(CK) AE1/3+++, CKCAM5.2+++, CD34BE12+, CK5+, CK6+, CK7++, CK14-, CK20+, EMA+, CDX-2-, CEA++, CA19-9++, CA125-, vimentin-, NSE-, NCAM-, synaptophysin-, chromogranin-, E-cadherin+++, beta-catenin+++, MUC1++, MUC2-, MUC5AC++, MUC6+, PSA+++, AMACR+++, AFP-, HepPar1-, p53-, KIT-, PDGFRA+, MET+, HER2-, Ki67+ (labeling = 5%). Myoepithelial cells were present in some areas. These results suggest the development and presence of a TVA in the PU indistinguishable from those in the GI tract, and it can arise from prostatic epithelium.