Relationship of Appendix with Ovary
Clinical Relationship in Mucinous Ovarian Tumors
The appendix has a critical pathologic relationship with mucinous ovarian neoplasms, with approximately 8% of mucinous ovarian tumors showing appendiceal involvement, necessitating mandatory appendectomy during surgical staging. 1
Surgical Management Guidelines
Appendectomy must be performed in all patients with mucinous ovarian tumors because of the significant risk of synchronous appendiceal pathology. 1 The NCCN guidelines explicitly state that appendectomy should be performed in all mucinous tumors and considered in all patients with epithelial malignancies suspicious for appendiceal metastases. 1
For non-mucinous ovarian cancers, the indications are more selective:
- Grade 3 tumors warrant appendectomy due to reports of the appendix being the only site of extra-ovarian spread. 1
- Routine appendectomy in early ovarian cancer remains controversial and is performed in less than 4% of cases. 1
- When gross tumor involvement of the appendix is visible, appendectomy is mandatory regardless of histologic type. 1
Pathologic Relationship
The appendix and ovary demonstrate several important pathologic connections:
Synchronous presentation is the hallmark, with mucinous tumors of both organs occurring simultaneously in over 90% of cases. 2, 3 When these tumors coexist, they typically share similar histologic features, ranging from cystadenomas to borderline tumors to invasive carcinomas. 2, 3
Bilateral ovarian involvement occurs frequently (approximately 44% of cases) when appendiceal tumors are present, with right-sided ovarian predominance when unilateral. 2, 3 This pattern, combined with mucin and atypical mucinous cells on ovarian surfaces, suggests potential secondary involvement from appendiceal primaries in some cases. 2
Origin Controversy
The site of origin remains debated:
- Some evidence suggests appendiceal tumors may be primary with secondary ovarian involvement, based on synchronous presentation, bilateral ovarian disease, and right-sided predominance. 2
- Conversely, other studies propose independent origins or multifocal neoplastic processes, as immunohistochemical markers show complete concordance in only one-third of cases. 3
- In practical terms, both organs should be considered potentially primary when mucinous tumors are encountered. 3, 4
Clinical Yield of Appendectomy
When the appendix appears grossly normal during surgery for mucinous ovarian neoplasms without pseudomyxoma peritonei, the yield is extremely low (less than 1% in one series of 155 appendectomies). 5 However, this does not negate the guideline recommendation, as grossly abnormal appendices harbor pathology in the majority of cases. 3, 5
Pseudomyxoma Peritonei Connection
Pseudomyxoma peritonei represents a critical complication of synchronous appendiceal-ovarian mucinous tumors, occurring when mucinous epithelium and mucin disseminate throughout the peritoneal cavity. 2, 3 This condition carries significant morbidity and mortality, with patients dying from disease progression years after initial presentation. 2
Common Pitfalls
- Failing to perform appendectomy in mucinous tumors is the most significant error, as 8% will have appendiceal involvement. 1
- Assuming a grossly normal appendix excludes pathology in the setting of pseudomyxoma peritonei—microscopic involvement may still be present. 3
- Not recognizing that carcinomatosis can result from two separate synchronous malignant processes (appendix and ovary) even without pseudomyxoma peritonei. 6