Metastatic neuroendocrine tumour mimicking endometriosis highlights the importance of excision for tissue diagnosis

Endometriosis is a common gynaecological condition, usually presenting with pelvic pain or infertility in women of reproductive age. Diagnosis is made on histopathology of deposits excised during laparoscopy, given diagnosis solely made by macroscopic examination can be challenging for even experienced gynaecological surgeons. A 45-year-old during laparoscopy for fibroids is found to have peritoneal deposits resembling endometriosis. Histopathology reveals multifocal metastatic grade 1 neuroendocrine tumour of the appendix. This incidental finding highlights the importance of thorough examination of the appendix and abdominal cavity for unexpected pathology during gynaecological laparoscopy. Incidental finding of appendiceal pathology at time of laparoscopy for endometriosis is not uncommon; however, the finding of metastatic malignancy is far rarer. While several case studies have reported severe endometriosis mimicking advanced stage cancer, this is the first documented occurrence of an advanced, metastatic tumour, mimicking endometriosis