Retrospective Analysis of Risk Factors Associated with Incidental Appendiceal Neoplasms in Patients with Acute Appendicitis

INTRODUCTION: As the nonoperative management of acute appendicitis becomes more widespread, identifying patients at high risk of appendiceal tumors is increasingly important. This study aimed to clarify the predictive factors of appendiceal tumors before appendectomy. METHODS: We retrospectively analyzed 434 patients diagnosed with acute appendicitis who underwent emergency or interval appendectomy. RESULTS: Appendiceal neoplasms were found in 3.9% of patients. Patients with tumors were significantly older (64.4 vs. 49.6 years, p < 0.001). The tumor group exhibited a lower appendicolith incidence (48% vs. 12%, p = 0.011) and larger appendiceal diameters (18.0 vs. 12.3 mm, p < 0.001). Multivariate analysis demonstrated that age ≥60 years, absence of appendicolith, and an appendiceal diameter ≥12 mm were independent risk factors of appendiceal tumors. Among patients who underwent interval appendectomy, only the non-tumor group exhibited significant improvement in appendiceal diameter after nonoperative management (tumor, +1.6 mm vs. no tumor, -3.5 mm, p < 0.001). CONCLUSIONS: Advanced age, absence of appendicolith, and an enlarged appendiceal diameter may be significant predictive factors of appendiceal tumors. These factors will aid in the selection of appropriate appendicitis treatment strategies.