The clinical and pathological features of low-grade appendiceal mucinous neoplasm (LAMN)

Abstract Introduction In this manuscript, we evaluated the clinicopathological features of low-grade appendiceal mucinous neoplasm (LAMN), a unique type of appendiceal tumors. Methods This is a retrospective study that included patients with LAMN who were presented to our center from January 2008 to December 2024. The epidemiological, clinical, pathological, therapeutic, and prognostic data were analyzed. Results A total of 68 patients were included in the study, with a median age of 55.8 years. Forty patients (58.8%) had pseudomyxoma peritonei (PMP) at the time of diagnosis. Surgical cytoreduction was used in 44 patients (65.7%), while appendectomy was performed in 23 patients (34.3%). HIPEC was used only in fifteen patients (22.4%). Gross perforation was identified in 7 cases (10.3%). While microscopically, micro-perforation or rupture was noted in 20 patients (29.4%). Adjuvant systemic treatment was used in 50% of the patients. Over a median follow-up of 18 months, recurrence occurred in 21 patients (31.8%), while five patients (7.4%) developed distant metastasis. Mortality rate was 20.5% (n=14), including five patients who died postoperatively, while nine showed tumor-related mortality. On univariate analysis, only adjuvant treatments showed statistically significant correlation with the incidence of recurrence (p=0.007). Conclusions The higher recurrence and mortality rates observed in our cohort compared with recent literature reflect the advanced disease burden and lower utilization of HIPEC. Future work should aim to refine patient selection for HIPEC, standardize operative approaches to minimize recurrence risk, and explore the role of adjuvant systemic therapy in reducing disease progression.