Abstract
Gastrointestinal stromal tumors (GISTs) are rare tumors that can arise anywhere in the tubular gastrointestinal tract. These tumors occasionally present as a pelvic mass, leading to a misdiagnosis of gynecological disease. A 47-year-old woman presented with a pelvic mass measuring 30 cm in diameter and highly elevated CA-125 levels. She underwent exploratory laparotomy with resection of the pelvic mass. The mass mimicking ovarian malignancy was found in the sigmoid colon and was correctly diagnosed as a GIST at surgery. It should be noted that preoperative diagnosis of GIST is uncommon, due to its rarity and the varying clinical presentation. However, non-gynecological tumors should be included in the differential diagnosis of a pelvic mass with atypical presentation. Gynecologists need to be cognizant of extra-ovarian pathology in patients presenting with an atypical pelvic mass.