Unusual Colonic Polypoid Mass Without Melanin Pigment Deposits

Abstract

Question: A 44-year-old woman presented with a 2-week history of rectal bleeding. A colonoscopy performed by her primary physician showed a polypoid lesion in the sigmoid colon, which was biopsied. The biopsy specimen demonstrated necrosis and inflammatory granulation tissue. Her only medication was an over-the-counter drug for weight reduction. The patient had no family history of colon cancer. She was referred for the management of the polypoid lesion. Physical examination was unremarkable and laboratory testing revealed no abnormalities. Repeat colonoscopy for polyp resection was performed and revealed a 1.2-cm polypoid lesion with hyperemic overlying mucosa in the sigmoid colon (Figure A). The rest of the colonic mucosa had a diffuse dark brown pigmentation, consistent with melanosis coli. An endoscopic mucosal resection using and inject-and-cut technique was performed, and the polyp was resected en bloc. Pathologically, the tumor was composed of abundant capillaries arranged in a lobular architecture (Figure B). The stroma was edematous and contained numerous lymphocytes, plasma cells, eosinophils, and neutrophils (Figure C). Most of mucosa was denuded. 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.