Endometriosis and its correlation with carcinoid tumor of the appendix: a systematic review

The prevalence of appendiceal endometriosis ranges from 0.4% to 22%. The carcinoid tumor is the most common neoplasm of the appendix, with incidence ranging from 0.3% to 0.9%. Appendix lesions develop in up to 22% of women with deep infiltrative endometriosis. Even though these are most likely endometriosis, carcinoid tumors should always be considered. The aim of this review was to assess the prevalence of appendiceal carcinoid tumors and appendiceal endometriosis in patients undergoing gynecologic surgery, its association with endometriosis, and related symptoms.

We included retrospective and prospective studies that assessed women who underwent appendicectomy in the past 20 years for appendiceal endometriosis and/or appendix carcinoid tumor confirmed by histological analysis. Results were reported as relative and absolute frequencies. Due to the heterogeneity of included studies, a statistical analysis (meta-analysis) was not performed.

The prevalence of appendiceal endometriosis was 15.2% in patients who underwent surgery for pelvic endometriosis and 11.4% in those who underwent benign gynecological surgery. Conversely, carcinoid tumors of the appendix were present in 2.4% of endometriosis patients and 1.3% of other benign gynecological surgeries.

The rates of carcinoid tumors in patients with endometriosis are the same as in the general population. Given the risk of a malignant appendiceal tumor, in all gynecological surgeries, especially those for endometriosis, the appendix should be inspected and removed if it has an abnormal appearance.