Nonetheless, no features of intrinsic appendicitis or malignancy were seen. The patient had a smooth recovery and was discharged on postoperative day 5, with further gynaecology follow-up. Endometriosis is the presence of endometrial glands and stroma outside the uterine cavity. Up to 6-10% of the general female population may be affected by this condition. 1 Intestinal involvement may occur in 3-34% of females with endometriosis; however, the sigmoid colon and rectum are most commonly affected. 2 Appendiceal endometriosis is rare with a reported incidence of 2.8%. 3 Symptomatic endometriosis of the appendix is highly variable in presentation and may mimic acute appendicitis or other general surgical pathology. Presentations including caecal intussusception, gastrointestinal perforation and per rectal bleeding have all been reported. 4 Differentiating these conditions can be highly challenging. Whilst endometriosis is familiar to gynaecologists, this case explores the atypical presentation and diagnostic challenges appendiceal endometriosis may pose to general surgeons, particularly the mimicry of familiar general surgical pathology. In our case, the patient's presenting symptoms and history were concerning for subacute appendicitis; however intraoperatively, malignancy was a differential diagnosis. Post-operatively, the patient's pain subsided, suggesting that the appendiceal endometrial deposits were the cause for symptoms. Nevertheless, in patients found to have appendiceal endometriosis, ongoing pain despite appendicectomy warrants investigation for other abdominopelvic endometrial deposits or nongynaecological diagnoses.