The Many Guises of Endometriosis: Giant Abdominal Wall Endometriosis Masquerading as An Incisional Hernia

Endometriosis is defined by the presence of ectopic endometrial tissue outside the uterine cavity. Despite being a lead cause of chronic pelvic pain and infertility, its clinical presentation can vary, leading to diagnostic and therapeutic challenges. Extra-pelvic endometriosis is particularly difficult to diagnose owing to its ability to mimic other conditions. Endometrial tissue in a surgical scar is uncommon and is often misdiagnosed as granuloma, abscess or malignancy. Cyclical haemorrhagic ascites due to peritoneal endometriosis is exceptionally rare. We report the case of a pre-menopausal, nulliparous 44-year-old woman who presented with ascites and a large abdominal mass arising from the site of a lower midline laparotomy scar. Five years previously, she had undergone open myomectomy for uterine fibroids. Soon after her initial operation she developed abdominal ascites, requiring percutaneous drainage on multiple occasions. We performed a laparotomy with excision of the abdominal wall mass through an inverted T incision. The extra-abdominal mass was of mixed cystic and solid components and weighed 1.52 Kg. It communicated with the abdomino-pelvic cavity through a 2 cm defect in the linea alba. The abdomen contained a large amount of odourless, brown fluid which was flowing into the mass. There was a large capsule covering the small and large bowel, liver, gallbladder and stomach. Final histology reported a 28cm x 19cm x 5cm mass of endometrial tissue with no evidence of malignant transformation. The patient recovered well post-operatively and remains asymptomatic at present. Our case illustrates that, despite being a common disease, endometriosis can masquerade as several other conditions and can be missed or diagnosed late. Delay in diagnosis will not only prolong symptoms but can also compromise reproductive lifespan. It is therefore paramount that endometriosis is considered early in the management of premenopausal women presenting with an irregular pelvic mass or haemorrhagic ascites.