Appendiceal Mucinous Neoplasm (AMN); A Case Series and Literature Review

Abstract Appendiceal Mucinous Neoplasms (AMN) are complex tumors of the appendix that’s made up of mucin-producing cells. Histologic differentiation is important, as well-differentiated tumors have a better prognosis. Frequently, appendiceal neoplasm is misdiagnosed because most patients are asymptomatic. The incidence of appendiceal tumors in appendectomy specimens is between 0.9 and 1.7%, with approximately one half of them being Low-Grade Appendiceal Mucinous Neoplasms (LAMN). We present a case series of 18 patients in whom mucinous appendiceal tumors were suspected/identified preoperatively by radiological exams, intraoperatively or after surgery at pathological examination. Seven patients have Pseudomyxoma Peritonei (PMP) at the time of diagnosis and 4 patients have mucinous carcinoma. LAMN were found in 13 cases. Twelve of 18 patients were female (66.7%) and the median age was 59 years (range: 42–84). Intraoperative findings varied from dilated appendices with mucinous content to large cystic masses involving adjacent structures with pseudomyxoma peritonei. Surgical interventions included laparoscopic appendectomy, open appendectomy, cecal resection and right hemicolectomy, with an emphasis on careful handling to prevent rupture and spillage of mucin. Seven patients required additional procedures, such as cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (hipec), due to the presence of pseudomyxoma peritonei or locoregional peritoneal diffusion. In conclusion, surgery has a critical role in the management of appendiceal mucinous neoplasms and postoperative management should involve a critical review of the pathopological examination, considering referral to a multidisciplinary team for higher-stage tumors and implementing long-term surveillance protocols due to the risk of recurrence