Deep infiltrating endometriosis mimicking colorectal cancer.

Abstract

Endometriosis is characterized by the growth of endometrial-like tissue outside of the uterus. When disease occurs greater than 5 mm beneath the peritoneum, it is known as deep infiltrating endometriosis (DIE).1 We describe a case of DIE involving the large bowel and surrounding lymph nodes presenting as a large bowel obstruction (LBO), mimicking malignancy. A 42-year-old female with worsening cyclical constipation, associated with over 20 kgs of unintentional weight loss, vomiting and dysmenorrhoea, was referred for a colonoscopy. No mucosal abnormalities were visualized, but the sigmoid colon was endoscopically impassable due to stenosis. Computed tomography colonography was performed, demonstrating sigmoid mural thickening suspicious for malignancy. Staging scans identified no abdominopelvic lymphadenopathy or features of metastatic disease (Fig. 1). The patient subsequently underwent a low anterior resection and had an uneventful recovery. The resection specimen showed localized, rubbery bowel wall thickening compressing and distorting the lumen. The serosa was mottled brown, from previous haemorrhage and haemosiderin deposition, with greyish-white fibrous puckering (Fig. 2). No features of malignant transformation were found. A diagnosis of DIE was confirmed due to the presence of endometrial glands and stroma throughout the bowel wall. Ectopic endometrial epithelium was also discovered in two pericolic lymph nodes (Fig. 3). Diagnosing DIE can be challenging as symptoms can be non-specific and definitive diagnosis with laparoscopic visualization is invasive. 5%–12% of endometriosis patients show bowel involvement and up to 90% of these cases will involve the sigmoid colon or rectum.1 This can result in bowel-specific symptoms, such as dyschezia, but LBO from DIE is rare, with an estimated incidence of 0.1%–0.7%.1, 2 Lymph node involvement is considered uncommon but has been increasingly reported in cases of rectosigmoid DIE, especially as deposits increase in size and more nodes are excised.3, 4 Although the pathogenesis is poorly understood, nodal involvement is thought to be due to lymphovascular spread of ectopic cells and is associated with an increased risk of disease persistence or recurrence.3-5 Surgical excision of DIE may assist in relieving intolerable or medically refractory symptoms.1, 6 Currently, there are few guidelines explaining which lesions benefit most from operative management or which surgical technique to follow. Shaving, discoid and segmental resection have all been proposed with differing risk–benefit analyses.1 Operative management needs to be carefully considered to balance complication risks against the possibility of disease persistence. However, when severe bowel obstruction is present, surgery is effective.1, 2 In female patients with unexplained gastrointestinal symptoms, DIE should be considered as a possible differential diagnosis. DIE involving bowel can mimic colorectal malignancy and therefore multidisciplinary management in complex DIE should be offered to these patients.1, 2, 6 Written informed consent was obtained from the patient for this case report and the use of these images. Carol Wu: Conceptualization; writing – original draft; writing – review and editing. Matthew Y. K. Wei: Conceptualization; supervision; writing – review and editing. Justin M. C. Yeung: Conceptualization; project administration; supervision; writing – review and editing. Shane Battye: Resources; writing – review and editing. Jin Cho: Conceptualization; resources; writing – review and editing.