[Clinicopathological analysis and surgical strategy of primary appendiceal neoplasms]

Objective: To investigate the clinicopathological features, surgical methods and prognosis of primary appendiceal neoplasms. Methods: A descriptive case series study was performed. Clinical data of patients diagnosed with primary appendiceal neoplasms in Peking University First Hospital from 2006 to 2017 were retrospectively analyzed. Patients who underwent surgery and were confirmed as appendiceal neoplasms by postoperative pathology were included. Cases of cecal tumor invading the appendix and other organ tumors implanting in the appendix and cases of recurrent appendix tumors were excluded Pathological classification was based on the 4th edition of the WHO classification of digestive tract tumors (2010 edition), and the efficacy of operation methods of low grade appendiceal mucinous neoplasm (LAMN) were analyzed. Results: A total of 115 patients were enrolled, including 52 males and 63 females with a median age of 59 (51, 71) years. Clinical symptoms usually manifested as dormant pain in the right lower quadrant, migrating right lower abdominal pain, fever and bloating. Twenty-four cases were accidentally discovered during surgery, and 21 cases were found by physical examination. The preoperative diagnosis rate of CT and ultrasound was 40.2% (43/107) and 25.5% (24/94) respectively. The postoperative pathological types contained 83 cases of LAMN, 12 cases of mucinous adenocarcinoma, 9 cases of appendiceal neuroendocrine neoplasms (aNEN), 2 cases of mucinous adenocarcinoma with signet ring cells, 3 cases of serrated adenoma, 2 cases of goblet cell carcinoid, 2 cases of lymphoma, 1 case of leiomyoma and 1 case of schwannomas. All the patients underwent surgical resection, including 41 cases of appendectomy, 21 cases of partial cecectomy, 48 cases of right hemicolectomy, and 5 cases of combined organ resection due to appendiceal tumor infiltration or dissemination. Eighteen cases were diagnosed with pseudomyxoma peritonei (PMP) during operation. A total of 98 patients were enrolled for follow-up. The median follow-up time was 58 (5-172) months. The 5-year disease-free survival (DFS) rate was 84.5% and 5-year overall survival (OS) was 88.2%. Multivariate analysis revealed that high-grade malignancy tumors (HR=25.881, 95% CI: 2.827-236.935, P=0.004) and PMP formation (HR=42.166, 95% CI: 3.470-512.439,P=0.003) were independent risk factors for prognosis. Patients undergoing right hemicolectomy presented longer operation time, more blood loss and higher morbidity of complication as compared to those undergoing appendectomy and partial cecectomy (all P<0.05), while no significant differences in 5-year DFS (P=0.627) and 5-year OS (P=0.718) were found. Conclusions: Primary appendiceal neoplasms usually have no typical features, accompanied with low preoperative diagnosis rate. The common pathological types are LAMN, mucinous adenocarcinoma and aNEN. Appendectomy or partial cecectomy for LAMN may achieve satisfactory prognosis. High-grade malignancy tumors and PMP formation are independent risk factors for prognosis.