Ulcerative Colitis-Associated Appendiceal Mucinous Neoplasms: A Systematic Review

Abstract Background Ulcerative colitis (UC) is a well-established risk factor for colorectal malignancy; however, primary appendiceal mucinous neoplasms (AMNs) remain a rare entity in this population. These lesions, ranging from benign cystadenomas to invasive adenocarcinomas, present significant diagnostic challenges as their symptoms often mimic UC flares or acute appendicitis. Given the scarcity of data and lack of standardized treatment guidelines, this systematic review aims to synthesize the clinical characteristics and management outcomes of AMNs in patients with UC. Aims This study aims to review the characteristics and management of appendiceal mucinous neoplasm in ulcerative colitis. Methods Inclusion criteria were adults with ulcerative colitis that presenting with appendiceal mucinous neoplasm under the histological confirm. Exclusion criteria were patient not affected by ulcerative colitis, not adults, lack of abstracts, articles that is not in English. We screened PubMed, Medline and Cochrane Library databases up to January 2026. Total 20 articles were included. Results This systematic review analyzed 29 patients (mean age 52 years; 55.2% male) with concurrent UC and AMNs. The majority had long-standing UC (mean duration 11.1 years among the 18 patients with available data), and 52% exhibited active colonic inflammation at the time of diagnosis. While abdominal pain was the primary symptom (48%), 14% of patients were asymptomatic with incidental findings. All patients underwent surgical resection, with procedures ranging from simple appendectomy (21%) to colectomy or proctocolectomy (38%). Histopathologically, benign mucinous cystadenomas were predominant (52%), while LAMN and mucinous adenocarcinomas each accounted for 27.6% and 20.7% respectively. These findings highlight that while most lesions are benign or low-grade, a significant proportion represents malignancy, necessitating high vigilance and careful surgical planning in UC patients. Conclusion Concurrent AMN and UC are rare. Diagnosis is challenging due to overlapping symptoms and nonspecific endoscopic findings. While most lesions are benign cystadenomas, the rate of malignancy (20.7%) and risk of pseudomyxoma peritonei necessitate rigorous preoperative imaging, and definitive surgical resection to ensure optimal outcomes.