The relationship between diverticula and low-grade mucinous neoplasm of the appendix. Does the diverticulum play a role in the development of periappendicular mucin deposition or pseudomyxoma peritonei?

Prevalences of diverticulum and low-grade mucinous neoplasm (LGMN) were reported as 0.04-2% and less than 1% in the appendix. In this study, the frequency of diverticulum in LGMN cases, the relationship between diverticula and periappendicular mucin, and the possible role of diverticula in pseudomyxoma peritonei pathogenesis were researched. Through systematic review and targeted search, 38 LGMN and 96 diverticula were identified, frequencies and relationship between diverticulum and LGMN were analysed. Diverticulum and LGMN were determined in 4.8% and 1.04%, respectively, of 1922 appendectomy materials specifically grossed by the same pathologist. The prevalence of diverticulum was higher in our study than literature. The difference may be due to detailed macroscopic examination. Diverticulum was detected in 60% of LGMN cases. The rate of diverticulum was found to be significantly higher in LGMNs than non-neoplastic diverticulum (p < 0.001). Periappendicular mucin deposition was significantly more frequent in LGMN cases with diverticulum than in other groups (p < 0.05). Follow-ups were available in 18 patients; none of them had mucin deposition in the peritoneal cavity. We detected that periappendicular mucin was highly associated with diverticula in LGMN cases. Periappendicular acellular mucin deposition may not give rise to pseudomyxoma peritonei. We may think that mucin could move out of the appendix through the diverticulum rather than neoplastic spread in some of these cases.