Endometrioma Within the Anterior Abdominal Wall Causing Cyclic Abdominal Pain

Lesions from endometriosis contain endometrial glands and stroma outside the uterine cavity. The lesions occur in the pelvis but are also found in the bowel, diaphragm, and pleural cavity. Endometriosis within the extraperitoneal abdominal wall is rare, though, and usually within c-section scars (incidence is .03%-.5%). The typical triad includes: mass in the abdominal wall, cyclical pain, and history of previous abdominal surgery. We present the case of a 28-year-old female with a past history of cesarean section and obesity (BMI = 31) who presented with approximately 3 years of abdominal pain which was "waxing and waning" in severity depending on her menstrual cycle. Multiple doctors and US imaging did not reveal a diagnosis. During consultation, she had a palpable 3 cm mass several centimeters above and right of her abdominal incision. She underwent a CT showing an inflamed subcutaneous mass abutting her anterior rectus sheath. She underwent wide excision which confirmed the diagnosis of endometrioma. This case demonstrates the need for good history and physical exam skills, as well as proficiency in reviewing radiographic imaging. Due to habitus and pain, the physical exam was difficult. However, there was a firm mass upon deep palpation. Her initial imaging was "negative," but review of the images revealed only intraperitoneal views and further imaging revealed the mass. There must be high clinical suspicion for this disease because failure to remove all tissue (including the surrounding fibrosis and desmoplastic tissue) or biopsy can lead to spread of residual endometrial cells and recurrence.