S1840 An Interesting Case of a Polyp in an Inaccessible Location: A Tubulovillous Adenoma Found in the Appendiceal Orifice

Abstract

INTRODUCTION: Primary adenocarcinoma of the appendix is a rare malignancy that accounts for less than 0.5% of all gastrointestinal malignancies. Of all appendiceal polyps, malignant adenomas of the appendix make up less than 0.1% of cases. We present an unusual case of a tubulovillous adenoma found in the appendix during a colonoscopy for evaluation of lower gastrointestinal bleed. CASE DESCRIPTION/METHODS: An 82-year-old man with a prior history of diverticular hemorrhage presented for complaints of hematochezia. A colonoscopy performed for evaluation revealed multiple diverticula. Incidentally, a 10 mm sessile polyp was seen at the appendiceal orifice extending into the appendiceal lumen. Biopsy of the lesion revealed tubulovillous adenoma. Patient subsequently underwent appendectomy and partial cecectomy. Pathology of the appendiceal specimen revealed a tubulovillous adenoma with moderate dysplasia. Citing age and personal reasons the patient has declined surveillance colonoscopy. He remains on aspirin for chemoprevention of further colonic polyps. DISCUSSION: Colonoscopy is the gold standard for screening and detection of neoplastic polyps to prevent their progression to carcinoma. Given the anatomy of the appendix and the difficulty of evaluating lesions extending into the appendiceal orifice, visualizing such lesions presents a tremendous challenge for endoscopists and are often missed during routine colonoscopy. While extremely rare, appendiceal polyps are often discovered accidentally during an appendectomy or incidentally at autopsy. Embryologically, the appendix is derived from the cecum and is thus histologically similar to colorectal tissue. 4.1% of patients with colorectal cancer also have synchronous appendiceal neoplasms. Recommended treatment is with appendectomy and, for malignant lesions, right hemicolectomy with subsequent surveillance colonoscopy. Overall five-year survival rate for appendiceal adenocarcinoma is 18.7%. However, this number jumps to 43.7% following curative resection. The difficulty of visualizing the appendix during colonoscopy has made detection of appendiceal neoplasms challenging. Furthermore, the association of colorectal cancer with appendiceal neoplasms and its favorable prognosis following resection, has placed an even greater emphasis on thorough visualization of the appendix during routine colonoscopy.Figure 1.: Sessile Polyp at the Appendiceal Orifice extending into Lumen.Figure 2.: Sessile Polyp at the Appendiceal Orifice extending into Lumen.