Low-grade Appendiceal Mucinous Neoplasm Causing Pseudomyxoma Peritonei and Review

Mucocele of the appendix is an obstructive dilatation of the appendix caused by the accumulation of mucinous material within the lumen. This rare condition occurs in 0.2-0.7% of all appendectomy specimens and is most commonly seen in individuals aged 50-60 years. Surgical intervention is always required and depends on the integrity and size of the appendix, base as well as the histological type of the original lesion. The prognosis is favourable if the appendix remains intact. However, perforation and subsequent leakage of its contents into the abdominal cavity can lead to pseudomyxoma peritonei, a condition with a very poor prognosis if not properly treated.

Low-grade appendiceal mucinous neoplasm (LAMN) is a rare condition, affecting approximately 1% of patients undergoing appendectomy. While LAMN is often asymptomatic, it can rupture and release mucin and neoplastic epithelial cells into the peritoneum, leading to pseudomyxoma peritonei. This condition produces abundant mucin or gelatinous ascites, commonly referred to as “Jelly-belly” syndrome.

Patients with LAMN without perforation have a better prognosis. However, those with perforation may experience symptoms similar to appendicitis, including pain in the right iliac fossa, fever, nausea, and vomiting. Increased mucin within the appendix lumen may present as a palpable mass or be diagnosed incidentally during an appendectomy.

For early-stage, non-perforated LAMN, a simple appendectomy is often adequate. In advanced stages, treatment may include appendectomy, right hemicolectomy, peritonectomy, and additional hypothermic intraperitoneal chemotherapy (HIPEC).

We report a rare case of low-grade appendiceal mucinous neoplasm leading to pseudomyxoma peritonei in a 56-year-old male patient. The diagnosis was made via ultrasonography and CT abdomen, identifying a perforated mucocele of the appendix.