An 84-year-old woman with a chief complaint of right lower abdominal pain was admitted to our hospital in November 20XX. Abdominal CT scan revealed a 9.6×4.1 cm diameter low density area proximal to the 13 mm diameter appendix, which led to perforated appendicitis with a huge abscess. The patient underwent an open appendectomy with partial cecum resection. The appendix was found to be twisted by 540°. The pathological diagnosis was low-grade appendiceal mucinous neoplasm(LAMN). Recent research has found that the use of laparoscopic surgery for the treatment of LAMN has been increasing. Appropriate surgical intervention should be considered for LAMN because it is a borderline malignancy. Careful treatment with laparoscopic surgery might be considered as one of the treatment options for LAMN. We hope to accumulate more cases of LAMN to confirm our results.