Clear cell carcinoma arising from abdominal wall endometriosis: a unique case with bladder and lymph node metastasis

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterine cavity. It affects about 15% of women of childbearing age. The most common site of endometriosis is in the pelvic cavity but it occasionally occurs in the extrapelvic area. Abdominal wall endometriosis represents 1% to 2% of all endometriosis lesions [1]. It is mostly found in umbilicus and incisional scars, especially following caesarean sections (CSs). Malignant transformation of abdominal wall endometriosis is a rare event and poorly understood. Most cases in the literature had local invasion. Here we report a unique case of clear cell carcinoma in abdominal wall endometriosis with bladder and lymph system metastasis.

A 39-year-old woman with a history of abdominal wall endometriosis presented to our clinic complaining of urgent urination and an emerging inguinal mass. She had a CS due to a breech presentation in 1994. She noticed a mass in the CS scar with cyclic pain in 1999. The mass was excised and diagnosed as abdominal scar endometriosis histologically. The margin was free and no further treatment was given after surgery. In 2004 a similar mass with cyclic pain was detected in the scar again. The mass grew gradually and was diagnosed as recurrent abdominal wall endometriosis without further treatment. She also developed urgent urination and dysuria during her menstrual period. In the last 4 months she noticed masses emerging in the bilateral inguinal area with mild pain.A physical examination showed a solid 6 cm × 5 cm mass without a clear borderline near the symphysis pubic in the previous longitudinal scar. Two enlarged lymph nodes with diameters of 2 cm and 1 cm in the right groin, and one lymph node with a diameter of 1 cm in the left groin were detected. Serum CA125 was 22.1 U/ml. Computed tomography (CT) scans showed that the mass had invaded the bladder and that the inguinal lymph nodes were enlarged (Figure 1). Cystoscopy showed that the mass had penetrated the roof of the bladder near the membrane (Figure 2). Malignant transformation of abdominal wall endometriosis was highly suspected before surgery.During laparotomy, it was seen that the mass had invaded the whole abdominal wall to the peritoneum and the roof of the bladder was also involved (Figure 3). There was no endometriosis detected in the pelvic cavity. A frozen section pathological analysis was done and malignant disease was confirmed. Therefore, the woman underwent extensive surgery including: partial bladder excision, hysterectomy, bilateral adnexectomy, omentectomy and lymph node excision. The inguinal lymph nodes, pelvic lymph nodes and para-aortic lymph nodes were all enlarged (Figure 4).Pathological examination gave a diagnosis of clear cell carcinoma in a background of endometriosis with metastasis to the bladder and the lymph nodes (Figure 5). There were 8/8 positive bilateral inguinal lymph nodes, 18/21 positive pelvic lymph nodes and 6/6 positive para-aortic lymph nodes.

The patient recovered uneventfully but refused further treatment after three cycles of chemotherapy with carboplatin and paclitaxel. She sought traditional Chinese herbal medication. Ten months after chemotherapy, tumor recurrence was detected in the pelvic cavity and the patient died of the disease two months later.

Malignant transformation of endometriosis in the abdominal wall is a rare complication and poorly understood. Symptoms of bladder invasion and lymph node spread could be a sign of malignant transformation. Local and lymph system invasion are two important routes for tumor metastasis. Extensive lymph node metastasis is probably related with poor prognosis.

Written informed consent was obtained from the patient for publication of this case report.