Sigmoidal Endometrioma; a Rare Subepithelial Lesion Mimicking Gastrointestinal Stromal Tumors: A Case Report

The ectopic endometrial tissue can be found in different places with no symptoms (such as intestinal endometriosis) and common symptoms such as abnormal bleeding, dysmenorrhea, and chronic pelvic pain. Early diagnosis and treatments, especially with surgical procedures, play an important role in patients’ recovery. We describe a 39-year-old woman with intermural and submucosal endometriosis. The compressive effect of the mass in the rectosigmoid colon caused digestive symptoms. After necessary procedures such as colonoscopy, computed tomography (CT) and endoscopic ultrasonography (EUS), we performed surgery, and the distal colon was resected. Ovarian cysts caused by endometrial tissue displacement can have symptoms similar to gastrointestinal stromal tumors (GISTs) if they are large enough to push through the gastrointestinal (GI) system. These symptoms can be diarrhea, abdominal tenderness, and so on. Surgery is the best diagnostic way for endometriomas and one of the diagnostic ways in GISTs. Also, with considering the drug resistance of GISTs to the current chemotherapy, the best treatment is also surgery. Location and tissue involvement of masses of the GI system are important points that should be considered in the differential diagnoses. In this way, early diagnosis and timely treatment, especially surgical, will have the best prognosis for the affected patients.