EXTRAPERITONEAL ENDOMETRIOMA: A RARE CAUSE OF ABDOMINAL PAIN

Objectives: Lesions from endometriosis contain endometrial glands and stroma, but occur outside the uterine cavity. Ectopic endometrial tissue can cause inflammation leading to dysmenorrhea, dyspareunia, infertility, and chronic pain. The lesions typically occur in the pelvis but are also found at other sites such as bowel, diaphragm, and pleural cavity. Endometriosis within the extraperitoneal abdominal wall is reported to be exceedingly rare. The majority of cases occur within cesarean section scars (although the incidence is only 0.03% - 0.45%), but 20% occur in a "scarless abdomen". The characteristic and typical triad includes: mass in the abdominal wall/incision, cyclical pain, and history of previous abdominal surgery.
We present the case of a 28-year-old female with a past medical history significant for cesarean section and obesity (BMI=31) who presented with approximately 3 years of abdominal pain that was most severe in her right lower quadrant. The pain was "waxing and waning” in severity depending on her menstrual cycle. She had seen numerous doctors and had numerous ultrasounds which revealed no abnormalities. On exam in the office, she had a palpable 3 cm mass just below the level of her umbilicus in the right lower quadrant. This was several centimeters above her abdominal incision. She underwent a CT scan which showed an inflamed extraperitoneal mass attached to 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 ultrasounds and radiographic imaging. In this case, the patient had classic signs and symptoms of an endometrioma. Given her obesity and pain, the physical exam was somewhat difficult, however, there was definitively a firm mass upon deep palpation. Her ultrasound imaging was negative, but review of the actual images revealed only intraperitoneal views. The CT scan revealed an obvious lesion, but there must be high clinical suspicion for this disease process before proceeding to the operating room or getting biopsy. Failure to remove all tissue in toto (including the surrounding fibrosis and desmoplastic tissue) or biopsy of the lesion can lead to spread of residual endometrial cells and recurrence.

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