A Lesion on Rectal Retroflexion

Abstract

Question: A 77-year-old woman presented with chronic constipation and intermittent episodes of painless hematochezia related to “hemorrhoids.” Prior colonoscopies were unrevealing. On digital rectal examination, no lesions were palpated. A colonoscopy was performed, which was unremarkable; there were no lesions seen as the colonoscope was withdrawn through the rectum and anal canal area. However, retroflexion of the instrument within the rectum demonstrated a distal rectal lesion (Figure A). It was unclear if this polypoid lesion was originating from the rectum or the anal canal. Given its proximity to the dentate line, it was biopsied (Figure B). What is the diagnosis? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. Figure B shows the histopathology of Bowen's disease (also known as squamous cell carcinoma in situ) with atypical squamous cells which have abundant eosinophilic cytoplasm and large nuclei. Carcinoma in situ is a noninvasive lesion defined as having malignant cells that have not penetrated the basement membrane. The condition was originally described by John T. Bowen in 1912.1Bowen J.T. Precancerous dermatoses: a study of two cases of chronic atypical epithelial proliferation.J Cutan Dis Syph. 1912; 30: 241-255Google Scholar Bowen's disease is used to refer to a dysplastic condition of the anal canal epithelium. However, the term “Bowen's disease” is not clearly defined in the literature and other terms used to describe dysplastic anal canal lesions include anal squamous intraepithelial lesions or anal intraepithelial neoplasia. As in our patient, anal bleeding is the most common symptom of anal canal carcinoma.2Ryan D.P. Compton C.C. Mayer R.J. Carcinoma of the anal canal.N Engl J Med. 2000; 342: 792Crossref PubMed Scopus (358) Google Scholar There is disagreement regarding the best treatment for Bowen's disease.3Chang G.J. Welton M.L. Anal neoplasia.Semin Colon Rectal Surg. 2003; 14: 111Abstract Full Text Full Text PDF Scopus (11) Google Scholar Our patient was treated as invasive T2 anal cell carcinoma with combined radiation and chemotherapy, because it was suspected that there was likely an invasive component given that the lesion involved one third of the circumference of the anorectal ring. One year later, she has no evidence of residual or recurrent disease. This case highlights 2 important points. First, painless rectal bleeding from anal squamous cell carcinoma can mimic hemorrhoidal bleeding and episodes of painless rectal outlet bleeding should not be attributed to internal hemorrhoids without an anoscopic examination. Second, this lesion would have been missed if the retroflexion maneuver had not been performed, thus illustrating the usefulness of rectal retroflexion in detecting neoplastic lesions.