Endometriosis Involving the Appendix Mimicking Acute Appendicitis and Appendiceal Tumor: Report of a Case

Endometriosis of the appendix is infrequent, and even rarer when it presents as appendiceal tumor. A case of endometriosis of the appendix that manifested as acute appendicitis and appendiceal tumor in a 44-year-old female patient is reported here. The woman visited the emergency room due to lower abdominal pain and high fever for 2 days. At ER, physical examination showed severe tenderness and rebounding pain at the McBurney's point. Abdominal computed tomography (CT) an Abdominal ultrasound suggested appendicitis with rupture. Therefore, she was immediately operated upon under the suspicion of acute appendicitis with rupture. Intra-operatively, an apparent appendiceal tip tumor with several enlarged mesentery lymph nodes was found. As appendiceal cancer with lymph node metastasis was highly suspected, a right hemicolectomy was performed. Later histological examinations showed endometriosis of the appendix and ileum, along with periappendiceal abscess. Post-operatively, the patient recovered with no residual pain.