Endometriosis of the Appendix: When Appendicitis Is Less Than Straightforward

We present a case report of a 49-year-old female with a history of ulcerative colitis who originally presented to the general surgery clinic after an incidental finding on computed tomography was concerning for a dilated, fluid-filled appendix. She ultimately underwent a laparoscopic appendectomy. The pathology returned consistent with early acute appendicitis, with endometrial tissue along the outer wall of the appendix. We then performed a literature review regarding appendiceal masses and the occurrence of endometriomas and/or endometriosis of the appendix. A PubMed search was performed using the key words of appendix and appendicitis and endometrioma. Specific articles were examined mentioning the occurrence of endometriomas of the appendix and isolated endometriosis of the appendix. Between 2% and 6% of cases of appendicitis present due to an appendiceal mass, usually an inflammatory phlegmon. A variety of other causes, including primary malignancy, secondary malignancy, and combinations of pathologies, may lead to the eventual removal of the appendix. Specifically, endometriosis of the appendix is reported in less than 1% of females on post-appendectomy pathologic analysis. Although specific symptoms may guide a provider, there are few distinguishing symptoms that would point a provider toward a different etiology, to include malignancy, for appendicitis. Further information is needed to determine when a patient has an increased risk for an underlying pathology when presenting with appendicitis. This information will help drive continued treatment and lead to improved screening for appendiceal masses.