Teratomas are mixed tumors that contain two or more of the three germ layer components. These most often occur in the gonads and in the mediastinum, retroperitoneum, sacrococcygeal region, and central nervous system. The incidence of SCTs is reported to be 1 in 35,000 to 1 in 40,000 live births, with a 4:1 female predominance . According to the Altman classification , SCTs can be divided into four types: type I, entirely outside the pelvis; type II, mostly outside the pelvis but with a small intrapelvic component; type III, mostly inside the pelvis, with a small external mass; and type IV, entirely inside the pelvis. Most type I and type II SCTs, which are easy to find, are diagnosed and resected in early childhood, but the reason why there are a small number of reports of adult cases is thought to be because most adult SCTs are type III and type IV, which are difficult to find. Most SCTs are benign, with only 1–2% showing malignant transformation, but the prognosis of malignant SCTs is poor, so prompt surgical resection is required [3, 6]. Taking into account the risk of recurrence or dissemination in cases of malignancy, preoperative pathological studies such as transcutaneous or transrectal biopsy should be avoided .
Complete surgical excision is the most acceptable treatment for SCT, and the main surgical approaches generally include transabdominal, transsacral, or a combination of both. The transabdominal approach is typically selected for high lesions and provides good exposure of the tumor posterior to the rectum. The transsacral approach is preferred for small tumors located in the lower portion of the pelvis. Although there are no clear selection criteria, the transsacral approach is considered to be a good option for tumors with a diameter of 10 cm or less and localization below the third sacral vertebra (S3) [2, 8]. Recent reports have documented that some SCTs can be safely excised laparoscopically, but in all cases, the transabdominal approach was applied [7, 9,10,11]. To the best of our knowledge, this is the first case report of a successful excision of an SCT by endoscopic surgery using a transsacral approach. This case featured a young woman who requested the skin incision to be as small as possible in consideration of esthetic and cosmetic results, and the tumor was 10 cm or less in diameter and below S3. Therefore, we chose a transsacral approach with endoscopic assistance. In the operation, the skin incision was limited to approximately 3 cm, and when it was difficult to remove the deep portion of the tumor through direct visualization, we attached GelPOINT® Path to the incision and insufflated it with the AirSEAL® System to excise the tumor endoscopically. We were able to excise the tumor without damaging the tumor or leaving residual tissue and did not cause complications, such as bladder and rectal dysfunction. This method is considered to be useful because the skin incision can be minimized and a safe operation can be performed with a stable field of view by ensuring a deep surgical field. However, if the patient has a large tumor or high lesion, careful judgment is required before selecting this procedure.