Obstructive endometriosis of the sigmoid colon with fistulation into ovarian teratoma

Abstract

A 44-year-old woman presented to the colorectal surgeons with a six month history of tenesmus and change in bowel habit. Initial investigations suggested a malignant colorectal tumour but biopsies showed squamous metaplasia and no colonic tissue. After further investigation and discussion at multiple multidisciplinary meetings, surgical resection of a large pelvic mass including sigmoid colon, uterus and ovary was performed. Histological examination of this mass showed intra-colonic polypoid endometriosis with fistulation through into an adjacent large cystic space, which was found to be a mature cystic teratoma. Both endometriosis and mature cystic teratoma of the ovary are common benign conditions, but this combination of pathologies does not seem to be common. The non-specific symptoms of her initial presentation made diagnosis difficult, along with the unexpected nature of the biopsies which did not fit with the endoscopic findings. This case required input from multiple specialties and multi-modal imaging and investigation.