Female with intermittently bleeding abdominal wall mass

A 39-year-old G1P1 female presented to the emergency department (ED) complaining of 1 year of intermittent bleeding from a left lower abdominal wall mass (Figure 1). The bleeding occurs monthly related to her menses. She had a cesarean section 10 years ago and first noticed the mass 6 years ago. She was diagnosed with endometriosis 3 years ago and takes Sprintec (norgestimate and ethinyl estradiol). On examination, the nodule was dusky-appearing, firm, minimally tender, and non-bleeding. The mass was evaluated with bedside ultrasonography (Figures 2 and 3). Endometriosis is defined as endometrial glands and stroma occurring outside the uterine cavity.1 Cutaneous endometriosis is relatively uncommon and occurs when endometrial glands and stroma reside in the skin.2 Cutaneous endometriosis is classified as primary or secondary. Primary cutaneous endometriosis appears without a prior surgical history and secondary cutaneous endometriosis, also called scar endometriosis, is associated with prior abdominal or pelvic surgery.3 It is hypothesized that endometrial cells dislodge during surgery, seeding the wound within and adjacent to the incision sites.4 Bedside ultrasonography was followed by a radiology ultrasound that showed a 1.2 × 0.4 × 0.9 cm simple fluid collection at the site of the C-section scar. Just inferior and deep to this fluid collection was an irregularly marginated, heterogeneous hypoechoic lesion with internal color-flow measuring ∼2.5 cm, compatible with an endometrioma. Because the patient was already taking Spintac, she was given return precautions and instructed to follow up with gynecology for further management.