2086 The Importance of Careful Appendiceal Inspection During Surveillance Colonoscopy in IBD Patients: A Case of Appendiceal Mucocele in an Ulcerative Colitis Patient

Abstract

INTRODUCTION: Appendiceal mucocele (AM) is a rare condition in which the appendix dilates and fills with mucus. These lesions can be benign or malignant and are classified into mucinous adenomas, low-grade appendiceal mucinous neoplasm (LAMN) and mucinous adenocarcinoma. Patients with inflammatory bowel disease (IBD) are at increased risk of colorectal neoplasia, but it is unknown whether IBD is associated with AM. CASE DESCRIPTION/METHODS: The patient is a 42-year-old female with a 24 year history of ulcerative colitis (UC) who presented with acute bloody diarrhea. She was diagnosed with UC at age 18, requiring treatment with cyclosporine and prednisone. She maintained steroid-free remission on mesalamine for 20 years before stopping treatment. She was clinically asymptomatic for 4 years until this acute flare. Colonoscopy revealed moderate to severe pancolitis with continuous and circumferential inflammation from the anus to cecum. A 2 cm × 1 cm submucosal mass was found within the appendix, concerning for AM or carcinoid tumor. CT showed appendiceal distention measuring up to 13 mm with a mucocele favored over chronic appendicitis due to the lack of periappendiceal edema. She was started on prednisone and mesalamine to improve the inflammation of the colon and decrease the risk of staple line dehiscence after surgery. Nearly 3 months later, the patient underwent an uncomplicated laparoscopic resection of the appendix and a partial cecectomy. Pathology revealed LAMN with negative margins. DISCUSSION: There is a low prevalence of primary appendiceal neoplasms and few reported cases of AM in IBD patients, the majority of which occurring in UC patients. Nevertheless, endoscopists should still be aware of the possible association between IBD and AM due to AM’s malignant potential. This abnormality can be subtle, so careful inspection of the appendix is warranted during routine colonoscopy. Rupture is a dangerous complication as intraperitoneal spread of malignant cells may lead to pseudomyxoma peritonei. Patients may present with right lower quadrant pain, abdominal mass, gastrointestinal bleeding, nausea, vomiting, weight loss and/or intussusception. Patients may also be asymptomatic with a bulging appendix incidentally found on colonoscopy. Diagnosis is further supported by CT or endoscopic ultrasound. Management is appendectomy with possible partial cecectomy or right hemicolectomy depending on tumor size, lymph node involvement, degree of atypia and IBD disease activity.