Mucinous neoplasms of the appendix

Last revised by Abenezer Zinaye on 10 Dec 2022

Mucinous neoplasms of the appendix are epithelial tumors of the appendix that produce mucin. They represent a spectrum of malignant potential, and are the most common cause of pseudomyxoma peritonei.

According to a panel of specialists consensus published in 2016 (Peritoneal Surface Oncology Group International), a nomenclature and classification for the appendiceal mucinous neoplasms based on histologic type and biologic behavior has been proposed 1-3:

These lesions have no capacity to cause pseudomyxoma peritonei:

It is important to note that in cases of peritoneal spread, the histologic grade of the peritoneal disease may be different than the primary appendiceal tumor. In these case, the peritoneal histology is considered more important for prognostication 3.

On imaging, they are difficult to be distinguished from each other, particularly when comparing the low- and high-grade appendiceal mucinous neoplasms, and generally are referred to as a "mucinous neoplasm of the appendix". 

Management varies depending both on the type of appendiceal tumor and (often more importantly) on the histology and extent of peritoneal disease. Surgical approaches, particularly for newer categories of disease (e.g. HAMN) remain under investigation 3.

In general, premalignant mucinous appendiceal tumors are treated by surgical resection. Indeterminate-behavior lesions such as LAMN are often followed with surveillance imaging after resection. Adenocarcinoma is generally treated with right hemicolectomy and nodal dissection, due to improved survival compared to appendectomy alone 3.

Patients with peritoneal disease (i.e. pseudomyxoma peritonei) may be treated by cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC), particularly if peritoneal disease is low-grade 3.

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Cases and figures

  • Case 1: LAMN
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  • Case 2: low-grade appendiceal mucinous neoplasm (LAMN)
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