Clear cell adenocarcinoma arising from abdominal wall endometriosis mimicking urachal tumor

A 41-year-old woman presented with severe lower abdominal pain. She had a history of 2 cesarean deliveries. Magnetic resonance imaging (MRI) revealed a 4.3 × 4.6 × 4.8-cm mass on the urinary bladder dome. Preoperative diagnosis was invasive urachal tumor. Wide resection of the tumor was performed. The histopathological diagnosis was clear cell adenocarcinoma with endometriosis. MRI revealed normal-sized ovaries and uterus. The definite diagnosis of clear cell carcinoma arising from abdominal wall endometriosis was made. Adjuvant chemotherapy with paclitaxel and carboplatin (total 6 courses) was planned. The patient has thus far received 4 courses of this treatment.