Clinical behavior of appendiceal mucinous neoplasia: 9 years of experience

Appendiceal mucocele is known a mucinous neoplasia of the appendix. It’s etiology is not clear. For last 30 years it’s incidence has increased to 2,8 cases/million person from 0,6 cases per million. Even if different classification has been made over the years, WHO and AJCC classifications are frequently used. Objective: The aim of this study was to find the pathologically performing the discrimination between LAMN and HAMN in the extracted specimen and how much the scattering mucin influenced the surgery and patients’ follow-up. Material and Methods: Patients and Centers: In two different hospitals between 2012-2020, the patients admitted to the emergency department and diagnosed as acute abdomen were evaluated retrospectively. All patients were accepted in the emergency clinic and operated then followed in the general surgical clinic. The appendiceal mucocele diagnosis was based on perioperative observation of mucinous distention or mucin dissemination. After obtaining specimens, the type of the mucinous neoplasm of appendix diagnosis and assessment was made by histopathological investigation. Results: Appendix mucocele was detected in 19 of 2974 patients included in the study. Two additional patients had advanced pseudomyxoma peritonei (PMP) after previous appendectomy. 11 of the patients (52.4%) were female. The mean age was 63.8 years. The appendix was evaluated preoperatively as enlarged in fourteen patients. In 1 patient, this condition was belonging to the ovary. Adeno cancer in one patient and PMP in 2 patients were clinically detected. Histopathologically, the appendix size was 37.1x71.9 mm. Sixteen of the patients were reported as LAMN, 2 as HAMN, 1 as adenocarcinoma and 2 as PMP. The leukocyte, carcinoembryonic antigen (CEA) and CA 19-9 levels of the patients were found to be significantly higher than normal. The patients were followed up for an average of 30.2 months. Early postoperative complications were seen in 5 patients. Complications evaluated late were seen in 8 patients. Recurrence was detected in one of the patients during the follow-up. The average survival rate was 36.7 months, although it was slightly higher in women. While the effect of leukocytosis, CEA, CA 19-9 on mortality was not significant, but tumor size was (p<0.05). This study has a few limitations. These are the small number of patients, the retrospective evaluation of the patients, and the relatively short follow-up time. Conclusion: In this study, we found mucocele more frequently than seen in the literature. Histopathologically, low grade mucinous neoplasia (LAMN) was often encountered. Mucocele with acellular mucin scattering were also seen in approximately 20% of the patients. After simple appendectomy, no recurrence was observed during the follow-up. The leukocyte count, tumor markers, and tumor size were evaluated in terms of their effects on postoperative morbidity and mortality. The tumor size had a negative effect on survival only. Finally, the simple appendectomy operation was considered suitable for the treatment.