Objective: Appendectomy is one of the most common surgical procedures. Histology usually confirms the clinical suspicion of acute inflammation, but sometimes other clinically relevant diagnoses are made. The aim of our study was to audit the appendectomies at our institution and summarise atypical pathological findings with emphasis on benign and malignant tumours. Method: We reviewed the histopathology results of 496 consecutive appendectomies received in a 5-year period. Results: Excluding three cases of metastatic process, appendiceal tumour was found in 21 cases (4.2 %), which is a higher rate than reported in the literature. There were four endocrine tumours, all G1, three cases of classical adenomas, 10 cases of low-grade appendiceal mucinous neoplasm (one associated with pseudomyxoma peritonei) and three cases of carcinoma (one mucinous adenocarcinomas, one intestinal type, one undifferentiated carcinoma). We also diagnosed one case of multicystic mesothelioma. Endometriosis was diagnosed in seven cases. In 18 cases appendicitis was associated with diverticula, in 6 cases changes were suggestive for Crohn's disease and in one case for cystic fibrosis. Negative appendectomy rate was 10.3 % that falls within the range reported in the literature. Conclusion: Histopathological examination of appendectomy specimens may reveal many different conditions not previously suspected; therefore, it should be performed in all cases. Results: CDX2, MUC1, MUC2, MUC5AC, and MUC6 expression was observed in 39.7 % (75 cases), 35.4 % (67 cases), 27.5 % (52 cases), 28.6 % (54 cases), and 16.9 % (32 cases), respectively. While SIAC patients with CDX2 expression showed less nodal metastasis (p=0.01), those with MUC1 expression tended to have SIACs with nodular or infiltrative growth (p = 0.003), poor differentiation (p = 0.005), and more lymphatic invasion (p=0.04). MUC5AC expression was associated with SIACs with well differentiation (p=0.02) and frequent pancreatic invasion (p=0.04). Patients with CDX2+/MUC1-had more polypoid (p=0.02) and well differentiated (p=0.006) tumors and a significantly better survival (median, 80.8 months, p<0.0001) than those with other immunophenotypes (CDX2−/MUC1+, CDX2+/ MUC1+, and CDX2−/MUC1−). Patients with CDX2 expression (median, 71.2 months) had a significantly better survival than those without CDX2 expression (23.0 months) by univariate and multivariate analyses (p<0.0001). Conclusion: CDX2 expression is an independent good predictor of survival in surgically resected SIAC patients.