Endometriosis of the vermiform appendix: a rare cause of acute abdomen in women – case report and review of literature

Introduction and importance: Appendicular endometriosis (AE) mimicking appendicitis is very rare. It has been reported only 44 times in the literature from 1975 to 2021. It is one of the causes of acute and chronic recurrent pelvic pain, associated with reduced quality of life, which improves after appendectomy. Case presentation: We present a rare case of isolated AE in a 19-year-old female, proven by histopathological examination, together with a short review of the literature. Discussion: We present a rare case of isolated AE. The definitive diagnosis is usually established following histopathological examination of the appendix. Laparoscopy is the procedure of choice for the diagnosis and surgical treatment of endometriosis of the appendix. In our case, there was an isolated AE. Our patient actually reported relief from spasmodic dysmenorrhea and chronic pelvic pain despite not having other sites of endometriosis except the isolated appendicular focus. Endometriosis of the appendix, or AE, is divided into primary and secondary forms. The primary form shows histopathological evidence of endometriosis within the appendix, with no clinico-pathological evidence of extra-AE. The secondary form is associated with internal and/or external endometriosis. There are two issues to be addressed in cases of AE. First is the prevalence of endometriosis of the appendix as an incidental finding in gynecological surgery. Second is the safety of appendectomy in women operated on for endometriosis (incidental or opportunistic appendectomy). Appendectomy at the time of primary gynecologic surgery is safe and does not increase the risks of the procedure. Additionally, several studies have shown that appendectomy does not significantly increase operating times. Conclusion: Endometriosis of the appendix, although rare, can present either as isolated appendiceal endometriosis (AE) or as part of pelvic endometriosis, in a single, pregnant, or even post-menopausal woman. It is a cause of lower quadrant abdominal pain and should always be considered in the differential diagnosis of young women complaining of nonspecific recurrent lower abdominal pain, especially in cases of infertility. Appendiceal endometriosis is associated with higher rates of perforation and abscess formation, and appendectomy should be considered if the appendix appears abnormal and should be sent for histopathological examination.