23: Rate of Neoplasia in Patients with Complicated Acute Appendicitis Managed Nonoperatively

Recent reports suggest the rate of neoplasia in patients with complicated acute appendicitis initially managed nonoperatively is higher than previously appreciated. The evolving role of nonoperative management of acute appendicitis highlights the importance in identification of appendiceal neoplasia. This study aims to ascertain the neoplasia rate in patients with complicated appendicitis treated nonoperatively and investigate potential predictors of malignancy.



Methods:

We conducted a prospective cohort study of all patients who presented to a tertiary care center with acute appendicitis between July 2019 and January 2023. Patients with complicated appendicitis were identified upon admission by a member of the research team. Complicated appendicitis was defined as radiographic findings of perforation, phlegmon or abscess. Patient demographics, clinical course, radiological findings, and pathologic information were systematically collected. Multivariable logistic regression analysis was performed to identify predictors of appendiceal neoplasia.



Results:

In total, we identified 1166 patients with acute appendicitis. Of those, 75 (6.4%) patients had complicated appendicitis treated nonoperatively (median age was 51 [IQR 37-68] years; 37 [50%] were female). Fifty-four (72%) patients ultimately had their appendix removed either due to failure of nonoperative management or interval appendectomy. Neoplasia rate among patients with complicated appendicitis initially treated nonoperatively was 16.0% (12/75). Out of the 12 patients with neoplasia, 6 had low grade appendiceal mucinous neoplasms, 4 had adenocarcinomas, and 2 had sessile serrated adenomas. Four patients went on to have a right hemicolectomy and 1 had CRS/HIPEC for peritoneal disease. Suspicion of malignancy on initial imaging was associated with increased risk of appendiceal neoplasia (OR 5.80, 95%CI 1.19-28.22, p=0.03). Age (< 40 vs ≥40), sex, appendicolith, abscess, size of abscess and initial white blood count were not significantly associated with appendiceal neoplasia.



Conclusions:

The rate of appendiceal neoplasia in patients with complicated appendicitis treated nonoperatively is high, regardless of age. Consideration of interval appendectomy in this population should be underscored, particularly in patients with suspicious features on initial imaging.