Endometriosis of the appendix presenting as acute appendicitis with unusual appearance

Endometriosis of the appendix is an uncommon mimicker of acute appendicitis which makes for a diagnostic dilemma.

We present a rare case of a menstruating woman presenting with classic symptoms of appendicitis, without the characteristic inflammatory changes seen on laparoscopy consistent with appendicitis. Instead, the appendix appeared unusually contracted on itself. Pathologic review of the appendix revealed microscopic findings of endometriosis.

We theorize the growth and shedding of the endometrial tissue during menstruation caused compression of the neural plexi in the wall of the appendix leading to the presentation mimicking acute appendicitis.

Given the potential for endometrial appendicitis, we propose appendectomy in reproductive age female patients with right lower quadrant pain, regardless of appendix appearance on laparoscopy.