Abstract
Scar endometriosis is a rare condition highly related to history of abdominal surgery. Due to the low incidence, it is often misdiagnosed. A woman presented to the surgery outpatient clinic with a mass near her C-section scar. Physical examination and ultrasound suggested Incisional Hernia while intraoperative finding revealed a mass suggestive of endometriosis which later confirmed by pathology examination. Scar endometriosis is a common subtype of extra-pelvic endometriosis. Iatrogenic transplantation is speculated to be its etiopathogenesis. Preoperatively, it is challenging to differentiate endometriosis from another abdominal masses. The definitive diagnosis is based on laparoscopy or surgery with histological verification. Chronic pain is complex and often involves multiple factors beyond simply a diagnosis of endometriosis, but it is important to think of endometriosis on women patients presenting with a mass and cyclic pain with history of surgery involving a large amount of endometrial cell.