Diagnosis of Appendiceal Adenocarcinoma during Screening Colonoscopy

Abstract

Purpose: Screening colonoscopy allows visualization of the colon and appendiceal orifice. Careful inspection of the appendiceal orifice can lead to identification of appendiceal pathology. Presentation: A 60-year-old man underwent colonoscopy for colon cancer screening. On inspection, the cecum appeared normal, however when air was aspirated prior to terminal ileum intubation, the tip of a pedunculated lesion prolapsed into the cecum from within the appendiceal orifice. Using a closed snare, a 15 mm polyp was everted from the orifice and removed by snare cautery. Clinical course: The post-procedure course was notable for fever and abdominal pain that developed 12 hours after the procedure. An abdominal CT scan showed stranding around the cecal base, consistent with injury from the procedure. Symptoms resolved with oral antibiotics. The pathology revealed a villous adenoma with high-grade dysplasia. The cauterized margins were positive for adenomatous epithelium. The CEA level was normal. An abdominal MRI showed a normal appendix. He underwent repeat colonoscopy which showed a persistent polyp within the appendiceal orifice. This was biopsied and the pathology showed villous adenoma. The patient then underwent an appendectomy with removal of 1.0 cm of the cecum. Results: Surgical pathology showed a moderately differentiated 0.3 cm mucinous adenocarcinoma present at the appendiceal ostium arising in a villous adenoma that encompassed the entire appendix and extended into the cecum. The margins were negative for adenoma or adenocarcinoma. Discussion: Villous adenoma of the appendix is rare, with a frequency of 0.02% in appendectomy specimens. Adenocarcinoma of the appendix has been known to arise from within these adenomatous lesions, however there are only four case reports of appendiceal adenocarcinomas being diagnosed preoperatively by endoscopy. Early-stage appendiceal adenocarcinomas can be cured by appendectomy or appendectomy plus cecectomy, however symptomatic patients are more likely to have unresectable disease. Other neoplastic lesions of the appendix reported to be visualized during colonoscopy include mucoceles, mucinous cystadenomas and carcinoid tumors. Caution should be exercised with attempts at mucosal resection; a few case reports describe appendiceal intussusception or invagination that may appear polyp-like, and endoscopic removal may lead to complications. Conclusion: Endoscopists should inspect the appendiceal orifice during colonoscopy and consider an appendiceal tumor when a polyp or deformity is seen.