PURPOSE: The factors that predict coincidental appendiceal neoplasms in patients who underwent appendectomy due to appendicitis were investigated. METHODS: 5829 patients diagnosed with appendicitis and underwent appendectomy in the department of surgery were examined. Among these patients, patients with appendiceal neoplasia and benign pathology were selected by propensity score matching analysis in a ratio of 1:4. As a result of analysis, 74 and 274 patients were grouped as appendiceal neoplasia and benign pathology, respectively. RESULTS: The mean age of the 348 appendiceal neoplasia and benign pathology groups included in the study was 45.6 and 46.4, respectively. Appendiceal diameter, contrast enhancement in the appendix wall, and neutrophil count were independent parameters for appendiceal neoplasia pathology. The AUC value of the combination of appendix diameter, lack of enhancement in the appendix wall, and neutrophil count in distinguishing appendiceal neoplasia pathology was 0.787. CONCLUSION: Appendix diameter, lack of wall enhancement, and neutrophil count are the three predictive indicators useful in helping clinicians suspect appendiceal neoplasms.