An incidental peritoneal serous borderline tumor during laparoscopy for endometriosis

Primary peritoneal serous borderline tumor (PPSBT) is an uncommon lesion, histologically indistinguishable from non-invasive peritoneal implants found in association with ovarian tumours of borderline malignancy.

A 37-year-old white woman was admitted for acute pelvic pain due to two 5 cm retrouterine bilateral ovarian cysts with an endometrioid aspect. Clinical examination, CA 125, transvaginal ultrasonography and magnetic resonance were used preoperatively to confirm the suspected diagnosis of pelvic endometriosis; conservative laparoscopy with an extensive pelvic toilette of pelvic scarring was performed to preserve her fertility. Surgeons performed cyst removal, detached bowel adhesions, removed all soft vesicular cysts and a soft blue nodule from the bowel, and coagulating all similar endometriotic islands in the pelvis. Surprisingly, the anatomopathological examination of samples revealed a rare PPSBT with diffuse implants on the bowel, bladder, and visceral and parietal peritoneum of the Douglas pouch.

Although PPSBT is a rare entity, it is nonetheless important because of its macroscopic similarity to endometriosis and microscopic similarity to other peritoneal and mullerian proliferations of both benign and malignant biologic potential. It should be considered in the differential diagnosis of endometrioid lesions on the peritoneal surfaces of visceral and parietal peritoneum in patients submitted for gynaecological problems.