‘Fortune cookie sign’: a variant of mushroom cap sign on T2 weighted MRI for deep sigmoid endometriosis

Excerpt

Nearly 15% of reproductive age women suffer from endometriosis. Deep pelvic endometriosis can affect the bowel in between 4 and 37% cases with the rectum and the distal sigmoid colon being the most common sites accounting for 75–90% of cases, due to proximity to the uterus [1‐3]. In a study demonstrating anatomical distribution of deep pelvic endometriosis, Chapron et al. [4] showed involvement of the rectosigmoid region in 65.7% cases and the sigmoid colon in 17.4% cases. Other less common sites included cecum and ileocaecal junction (4.1%); appendix (6.4%); small bowel (4.7%) and omentum (1.7%). Rectosigmoid endometriosis is generally associated with obliteration of the pouch of Douglas and dense adhesions with coalescence of uterus and anterior rectal wall. The ectopic endometrial tissue can infiltrate the bowel wall extending from serosa into the mucosa, forming a nodule or a mass with folding of the rectal wall in a characteristic appearance as a ‘mushroom cap’. The mushroom cap sign is an important and specific feature on T2 weighted MRI representing deep rectosigmoid endometriosis with submucosal infiltration [5, 6]. …