Acute appendicitis due to appendiceal endometriosis: Two case report and literature review

Appendiceal endometriosis (AE) is a rare condition, with a prevalence ranging from 0.05 % to 1.7 % in patients with endometriosis. It represents <1 % of cases of acute appendicitis (AA).

We present two cases of AA where the histological cause was endometriosis. Both cases involved patients around 40 years old who presented with abdominal pain in the right iliac fossa. AA was diagnosed through abdominal computed tomography (CT), which in the first case showed acute appendicitis, successfully treated with laparoscopic appendectomy. In the second case, the CT showed signs of an appendiceal phlegmon, initially treated non-operatively with poor response, leading to exploratory laparoscopy and abscess drainage 48 h later. Subsequently, a scheduled laparoscopic appendectomy was performed after 6 months. Histopathological diagnosis in both cases was AA due to AE with endometrial glands showing recent bleeding, causing hyperplasia of the appendiceal muscular layer.

Endometriosis, characterized by the presence of endometrial tissue outside the uterine cavity, can rarely affect the appendix, termed AE. AE, though uncommon, poses diagnostic challenges due to nonspecific imaging findings and variable presentations, ranging from asymptomatic cases to AA. Histological evaluation post-appendectomy is definitive for diagnosis. AE is associated with right-sided pelvic involvement and often requires surgical management, with appendectomy typically resolving acute symptoms. However, recurrence of cyclical pain due to pelvic endometriosis may persist, underscoring the importance of comprehensive evaluation during laparoscopic procedures.

AA caused by AE is an uncommon condition, with very difficult preoperative diagnosis based solely on personal history, clinical presentation, and even imaging studies. It should be considered in differential diagnoses for women of reproductive age with associated pelvic endometriosis, although the recommended treatment in all cases is surgical.