Partial Resection of a Tailgut Cyst Attached to the Rectum via a Transcoccygeal Approach: A Case Report With a Favorable Outcome.

A tailgut cyst is a congenital cystic tumor that develops when the tailgut, derived from the hindgut in early embryonic development, fails to naturally regress and remains in this presacral space. Treatment typically involves surgical resection due to the possibility of cyst infection and neurological symptoms from compression. Various surgical approaches exist, including abdominal, transanal, and transsacral approaches. We report a case where partial resection of a tailgut cyst attached to the rectum was performed via a transcoccygeal approach, resulting in a favorable outcome. The patient was a 20-year-old female with no significant medical history who had experienced constipation since middle school. At age 19, she developed urinary retention, and examination at a local clinic revealed a presacral cystic mass, leading to referral to our hospital. Upon presentation, she had constipation and urinary retention but no apparent neurological abnormalities. Blood tests were normal, and a pelvic MRI showed a 12 cm cystic mass posterior to the rectum. CT-guided aspiration revealed cloudy, yellowish, highly viscous fluid with no evidence of malignancy. Based on the fluid characteristics and imaging findings, a tailgut cyst was diagnosed. A transcoccygeal cyst resection was performed by transecting the bone distal to the sacral hiatus and mobilizing the coccyx. However, the tumor was adherent to the peritoneum and posterior rectal wall, resulting in partial resection. Pathology showed a cystic lesion lined with non-keratinizing stratified squamous epithelium and granulation tissue, with no malignant findings. Recurrence was noted two weeks postoperatively, and while complete resection was considered, the patient wished to avoid a colostomy. A second surgery using the same approach was performed, with maximal tumor dissection from peritoneal adhesions. Complete dissection from the posterior rectal wall was impossible, suggesting the tumor originated from this area. The remaining tumor was treated with holmium YAG (yttrium aluminum garnet) laser irradiation and anhydrous alcohol injection. MRI one month postoperatively showed complete cyst resolution, and after three years, there was no recurrence with good bowel and bladder function. We report a case of successful partial resection of a tailgut cyst attached to the rectum via a transcoccygeal approach. When the lesion invades the rectum, complete resection would necessitate a colostomy. However, in cases without malignant findings, choosing this minimally invasive approach with partial tumor resection and observation of the remaining rectal invasion site may be a viable option.