A Case of Low-Grade Appendiceal Mucinous Neoplasm That Led to Surgery After 12 Years of No Treatment.

Low-grade appendiceal mucinous neoplasm (LAMN) is a relatively rare, non-invasive appendiceal tumor. We experienced a case of LAMN that led to surgery after 12 years of no treatment. Until now, LAMN has been reported to progress more slowly than other tumors, but there have been no reports of long-term follow-up of appendiceal tumors without treatment. Although the tumor had grown over the course of 12 years, there was no mixing or migration of other histological types, and it did not lead to pseudomyxoma peritonei. As this course is considered to be relatively rare, we report it along with a literature review.