Laparoscopic surgery of a presacral epidermoid cyst: A case report

Highlights • The best approach for resecting epidermoid cysts is still controversial.• We successfully performed laparoscopic resection of an epidermoid cyst.• Laparoscopic resection may be a better option in carefully selected cases.• However, the tumor size and location must also be considered.


Introduction
Epidermoid cysts that developing the presacral cavity are rare congenital cystic tumors. They are mostly benign tumors, but they reportedly have risks of infection, fistula, and malignancy [1]. Therefore, surgical resection is recommended. Their anatomical location makes them difficult to reach, so they have traditionally been accessed through a posterior or transabdominal approach. The best approach is still controversial. Recently, a successful laparoscopic approach has been reported [2]. Laparoscopic surgery can provide magnification of the visual field and reachability into the deep pelvis with forceps. It is possible to perform surgery with laparoscopy more safely and less invasively. Herein, we describe a case of an epidermoid cyst in which laparoscopic resection was performed successfully. This case report has been written in line with the SCARE criteria [3].

Presentation of case
A 50-year-old woman was referred to our hospital for further examination of a cystic tumor in the pelvis that was incidentally detected by computed tomography (CT) during evaluation for upper abdominal pain. She had no past medical and surgical history. On digital rectal examination, a soft mass was palpated outside of the rectal wall. Laboratory findings indicated that the carbohydrate antigen 19-9 level was within the normal limit (11.3 U/ml), but the carcinoembryonic antigen level was slightly high (7.2 ng/ml). A colonoscopy showed no tumorous lesions. Contrast-enhanced CT revealed a 63 × 55-mm well-defined, homogeneous cystic mass in the left dorsal side of the rectum and ventral side of the coccyx. Magnetic resonance imaging (MRI) showed a unilocular cystic tumor with a low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and high signal intensity on diffusion-weighted images (Fig. 1). The tumor was diagnosed as a developmental cyst based on the radiological findings, and laparoscopic resection was performed.
The patient was placed in the lithotomy position. Access to the tumor was gained with by using a 10-mm umbilical port with the Hasson technique, followed by four 5-mm ports in both the right upper/lower and left upper/lower quadrants. The uterus was fixed to the anterior abdominal wall with sutures. The tumor was placed along the left lateral side of the rectum ( Fig. 2(a)). When the peri-   toneum was incised, a capsulated tumor was observed, and the caudal side of the tumor continued up to the level of the levator -ani ( Fig. 2(b)). Resection around the whole circumference of the tumor was performed by using the Harmonic and the electric scalpel without adhesion to the surroundings (Fig. 2(c)). There was no injury to the rectum. The operating time was 192 min, and total blood loss was 30 ml.
Macroscopically, the tumor formed a 40 × 35 × 30-mm cystic wall filled with mucoid, yellowish-colored fluid. Microscopically, the inner surface of the cyst was lined with stratified squamous epithelia ( Fig. 3(a)-(c)). The histopathologic diagnosis was an epidermoid cyst, and there was no evidence of malignancy.
No postoperative event occurred, and the patient was discharged on postoperative day 5. Six months postoperatively, there was no signs of recurrence.

Discussion
The presacral cavity is the space bounded by the rectum in the anterior direction, sacrum/coccyx on the posterior side, peritoneal reflection in the cranial margin, and anterior sacrococcygeal ligament and coccygeus muscle on the caudal [4]. Presacral tumors are uncommon with an incidence of 1/40,000-63,000 patients [5,6] and 60% of presacral tumors are congenital [5]. The term "developmental cysts" was defined as presacral congenital cystic tumors produced by developmental error in the embryonal phase, and these cysts were thought to arise from caudal embryonic vestiges [7]. They occur mostly in middle-aged women [1]. Developmental cysts can be pathologically divided into epidermoid cysts, dermoid cysts, or tailgut cysts [7]. Both epidermoid cysts and dermoid cysts are lined with stratified squamous epithelia, but dermoid cysts also contains skin appendages. Tailgut cysts are lined with various epithelia, such as columnar cells, squamous cells, and transitional cells [1,7]. Malignant transformation of developmental cysts is rare, but it has been reported in the literature [8].
CT and MRI are useful in diagnosing presacral tumors. It has been reported that a low signal intensity appears on a T1-weighted image and high signal intensity appears on a T2-weighted image. Epidermoid cysts contain fatty elements, such as desquamated debris, cholesterol, keratin, and water [9]. A preoperative biopsy should not be performed because it can lead to tumor dissemination, abscess, fecal fistula, or meningitis [5].
Epidermoid tumors are located anatomically deep within the pelvis, and they are difficult to reach. Therefore, they have been traditionally accessed through sacral, abdominal, or a combined abdomino-sacral approach. The best approach is determined in consideration of the size and location of the tumors. An abdominal approach is preferred in the case of tumors developing on the cranial side. It is safe to use an abdominal approach to recognize locate the anatomical component in the pelvis easily, but this approach is more invasive because it requires a larger incision. If the tumor is small (≤10 cm), located at the caudal level (below S4), and has not invaded surrounding structures, a sacral approach is often selected [10]. This approach is less invasive than the abdominal approach, but it is provides limited surgical space. If the coccyx and sacrum are partially excised, there is a risk that pain will remarkably persist postoperatively. Furthermore, since the incision wound is near the anus, the risk of wound infection is considered to be increased [11].
In our patient, there was no difficulty in the field of view and forceps operability during laparoscopic surgery. Since an epidermoid cyst is a well-defined lesion, ablation between the tumor and muscle is easy because of the magnifying effect of the laparoscope. Furthermore, it is possible to perform laparoscopic surgery with minimal damage to the muscles, nerves, and rectum, leading to the preservation of anal function. However, a longer operating time may be required.
Laparoscopic surgery is considered to be one of the options in terms of its minimal invasiveness, reduced risk of complications, and complete tumor removal. Laparoscopic resection of an epidermoid cyst might be implemented in carefully selected cases with consideration of the tumor size and location.

Conflicts of interest
There are no conflicts of interest.

Funding
There are no study sponsors or sources of funding.

Ethical approval
No ethics committee approval is required at our institution for a case report involving a single patient.

Consent
Written informed consent was obtained from patient for publication of this case report and accompanying images.

Author contribution
1 Koichi Mohri wrote the paper and did data collection and interpretation. 2 Tadahiro Kamiya, Kazuhiro Hiramatsu, Yoshihisa Shibata, Motoi Yoshihara, Taro Aoba, Akira Ito, and Takehito Kato reviewed this article and approved.