Brenner Tumor Presenting as a Retrorectal Mass with Prior Hysterectomy and Salpingo-Oopherectomy

Introduction

Retrorectal masses are rare, with an incidence of approximately 1 in 50,000. ¹ These masses usually originate from embryonic remnants and have a wide differential diagnosis, with cases reported as epidermoid cysts, hamartomas, ganglioneuromas, hemangiopericytomas, chordomas, sarcomas, angiogenic tumors, gastrointestinal stromal tumors, endometriosis, or other congenital cysts, as well as malignancies.^2–4 This article reports on the case of a retrorectal mass of unusual origin.

Case

A 45 year-old gravida 0 had a prior right salpingo-oopherectomy followed by a total abdominal hysterectomy with a left salpingo-oopherectomy for endometriosis. Five (5) years after her procedures, she underwent imaging secondary to a motor-vehicle accident and was found on computed tomography (CT) scan to have a pelvic cystic mass. The mass was initially followed conservatively as this patient was asymptomatic and imaging was most consistent with a lymphocele. Approximately 2 years later, the patient had another CT scan showing the mass again, but this time, it was slightly larger at 8 X 5 X 5cm. The mass was most consistent with a peritoneal inclusion cyst, or lymphocele, and was intimately involved with the lateral and posterior aspects of the rectosigmoid colon. The patient complained of worsening lower abdominal and pelvic pain but stated that she had normal bowel function. On examination, the patient had some pelvic tenderness. The cervix, uterus, and adnexae were surgically absent. The parametria were free of disease and the mass was not palpable. Because of the expected benign nature of the lesion, the patient underwent CT guided drainage of the mass.

Approximately 100 mL of fluid was removed that was predominantly acellular and insufficient for diagnosis. A follow-up CT scan 4 months later showed that the mass was now 6 cm in diameter. The patient was still symptomatic but had a strong desire to avoid surgery. A follow-up scan was scheduled for 3 months later. The mass was followed conservatively at the patient's request. Thirteen (13) months later the patient had a worsening of her pelvic pain and requested surgical intervention. Magnetic resonance imaging (MRI) showed that the mass had grown to 11 X 5 X 6 cm (Fig. 1). The physical examination was unchanged. The patient was scheduled for an exploratory laparotomy.

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FIG 1.

T2-weighted axial magnetic resonance imaging of a cystic mass (single arrow) displacing the rectum (double arrow).

At laparotomy, washings were done. An extensive adhesiolysis was performed to free redundant loops of large bowel from the pelvic sidewalls and the vaginal cuff. The left ureter was extremely adherent to the mass. Dissection was performed to free the mass, which was sitting on the sacrum and extending down retrorectally. The mass entered the retrorectal space and displaced the rectosigmoid colon to the right. A small 2 X 1 cm solid nodule was also found within the mass. These specimens were sent for permanent section. The remainder of the procedure was uneventful, and no other masses or disease were noted.

Results

The final pathologic diagnosis was a benign ovarian Brenner tumor with a fragment of fallopian tube, including a paratubal serous cyst. All washings and specimens were negative for malignancy. The patient had an unremarkable postoperative course.

Discussion

Retrorectal masses primarily arise from the gastrointestinal tract, sacrum, or coccyx, and are often of congenital origin.^1,2 The workup for detecting retrorectal masses has been described elsewhere. ³ As in this case, a preoperative workup using MRI or CT can be very useful for planning the surgical route used for diagnosis and cure. ⁵ Even though radiology was able to gain access to the mass, a preoperative diagnosis was not possible with the fluid obtained. In this case, the mass could have originated at the distal aspect of the lesion and grown superiorly, or it could have originated superiorly and grown inferiorly. Therefore, it may not always be possible to determine the origin of a retrorectal mass.

Conclusions

MEDLINE^® was searched for references, using the terms retrorectal ovary, ovarian, mass, and rectum, and no reports of retrorectal masses of ovarian origin were found. The differential diagnosis of a retrorectal mass should be expansive and include ovarian and fallopian-tube tumors.