Objective: To investigate the clinicopathologic features of epithelial appendiceal neoplasm presented with appendicitis. Methods: Specimens from 15 patients of epithelial appendiceal neoplasm associated with appendicitis were retrospectively analyzed using clinicopathological method. Results: Fifteen cases were evaluated, including 9 precursor lesions (8 serrated lesions and 1 villous tubular adenoma) and 6 low-grade appendiceal mucinous neoplasms (LAMN). Serrated lesions were subclassified as 6 sessile serrated adenoma/polyps (SSA/P) and 2 traditional serrated adenomas (TSA). Fourteen cases presented with acute appendicitis, while 1 case with symptoms of chronic appendicitis. Microscopically, sawtooth structure, basal crypt dilation and L- or inverted T-shaped crypt was observed in SSA/Ps. TSAs demonstrated obvious serration, ectopic crypt and cellular dysplasia. The muscularis mucosae was intact in serrated lesions. LAMNs were characterized by mildly atypical mucinous epithelium, fibrosis or rupture of the wall and acellular mucin in the wall and serosa. Follow-up was available in 9 cases, including 5 precursor lesions and 4 LAMNs. The follow-up interval ranged from 1.0 to 81.5 months. All patients were alive without disease. Conclusion: Appendiceal serrated lesions and LAMNs may be presented with symptoms of acute appendicitis, serrated lesions are usually detected as incidental lesions on microscopy. Appendiceal epithelial tumors should be keep in mind to avoid iatrogenic perforation causing peritoneal pseudomyxoma. Specimens of the appendix should be entirely submitted in order to differential diagnosis and assess the status of margin.