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:
Uncertain malignant potential
low-grade appendiceal mucinous neoplasm (LAMN)
- typically do not cause nodal or distant extraperitoneal metastases 3
- high-grade appendiceal mucinous neoplasm (HAMN)
- appendiceal mucinous adenocarcinoma
- poorly differentiated (mucinous) adenocarcinoma w signet ring cells - ≤50% signet ring cells
- (mucinous) signet ring cell carcinoma - >50% signet ring cells
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".
Treatment and prognosis
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.
- 1. Carr NJ, Cecil TD, Mohamed F, Sobin LH, Sugarbaker PH, González-Moreno S, Taflampas P, Chapman S, Moran BJ. A Consensus for Classification and Pathologic Reporting of Pseudomyxoma Peritonei and Associated Appendiceal Neoplasia: The Results of the Peritoneal Surface Oncology Group International (PSOGI) Modified Delphi Process. The American journal of surgical pathology. 40 (1): 14-26. doi:10.1097/PAS.0000000000000535 - Pubmed
- 2. Leonards LM, Pahwa A, Patel MK, Petersen J, Nguyen MJ, Jude CM. Neoplasms of the Appendix: Pictorial Review with Clinical and Pathologic Correlation. Radiographics : a review publication of the Radiological Society of North America, Inc. 37 (4): 1059-1083. doi:10.1148/rg.2017160150 - Pubmed
- 3. Legué LM, Creemers GJ, de Hingh IHJT, Lemmens VEPP, Huysentruyt CJ. Review: Pathology and Its Clinical Relevance of Mucinous Appendiceal Neoplasms and Pseudomyxoma Peritonei. (2018) Clinical colorectal cancer. doi:10.1016/j.clcc.2018.11.007 - Pubmed
Related Radiopaedia articles
The appendix can be affected by numerous inflammatory, infectious and neoplastic conditions:
- appendiceal diverticulitis
- appendiceal mucocele
- appendiceal intussusception
neoplasms of the appendix
- appendiceal epithelial neoplasms
- Goblet cell carcinoid of the appendix
- appendiceal neuroendocrine tumors
- appendiceal lymphoma