title: A novel submucosa nodule of the rectum: A case of the ectopic prostatic tissue outside the urinary tract.
abstract: Ectopic prostatic tissue is an underreported entity, which is found most commonly in the lower male genitourinary tract, and ectopic prostate tissue outside the urinary tract is even rarer. Our patient was a  unique case of ectopic prostatic tissue within submucosa of the rectum. The patient presented with rectal bleeding, and a firm, round solid submucosa nodule found in the anterior rectum at digital rectal examination, it was 1cm in diameter and 5cm above the anal verge. The size and submucosa location of this nodule were confirmed by the colonoscopy and MRI. After being removed surgically, the histopathology of the specimen sections possessed typical prostatic acini and stroma, meanwhile the immunohistochemical staining for prostate specific antigen confirmed its' prostatic nature. It is the first case to date, which involves the mural of rectum. We hypothesizes that the etiologies of ectopic prostatic tissue within the submucosa rectum attribute to embryogenetic abnormality.
authors.affiliation: Sheng Dai, MD, Department of the Colorectal Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, P.R. China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Dai
authors.affiliation: Xuefeng Huang, PhD, MD, Department of the Colorectal Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, P.R. China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Huang
authors.affiliation: Weifang Mao, MD, Department of the Colorectal Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, P.R. China.
authors.forename: Weifang
authors.initials: W
authors.lastname: Mao
keywords: Ectopic prostatic tissue; Embryogenesis; Immunohistochemical staining; Prostate specific antigen; Rectal submucosa