# A unique case of appendiceal diverticulum presenting with positive faecal immunochemical test

## TL;DR

A 70-year-old woman with a positive bowel cancer screening test was found to have a rare appendix condition called appendiceal diverticulum, which can mimic cancer and cause false positives.

## Contribution

This case highlights appendiceal diverticulum as a rare but important cause of a positive faecal immunochemical test in asymptomatic patients.

## Key findings

- A positive faecal immunochemical test in an asymptomatic patient led to the discovery of appendiceal diverticulum.
- Appendiceal diverticulum can present as a mass at the appendiceal orifice during colonoscopy.
- Histology confirmed the diagnosis after surgical removal of the appendix and a small part of the cecum.

## Abstract

Appendiceal diverticulum is a rare condition that usually presents with symptoms similar to acute appendicitis. Although imaging can be used to aid the diagnosis of this condition, it is usually confirmed postoperatively on the basis of histology. Because of an increased risk of appendiceal neoplasms, the usual management is prophylactic appendicectomy. We report the case of a 70-year-old lady with no symptoms referred from her GP surgery for a positive faecal immunochemical test as part of the bowel screening programme. Colonoscopy showed a mass at the appendiceal orifice with normal histology. She underwent an appendicectomy with a small cuff of caecal resection. The lesion was ~8 cm at its maximum dimension and showed appendiceal diverticulum. Appendiceal diverticulum is an important differential diagnosis to consider in patients with atypical history of acute appendicitis or positive faecal immunochemical test with no other symptoms.