Today a patient came to the hospital with a very small sacral cyst, a single cyst. However, the pain in the perineum and posterior thigh is very severe and getting worse. After going to many doctors, they generally recommended conservative observation. Various tests were done and no other diseases were found. Finally, she and her family made up their mind that even if the pain had nothing to do with this cyst, it should be cut out because only this one problem was detected and the operation itself was safe enough. Intraoperatively, it was found that the cyst, although small, had high internal pressure, indicating that even small cysts can cause nerve compression. A cyst wall folding suture was done as well as a leak closure and the cyst disappeared completely. The postoperative pain was significantly relieved and will be further relieved in the future, with an estimated full recovery in about six months. The lesson from this case is that small cysts can also cause serious symptoms and minimally invasive surgery can be done if other related diseases can be ruled out. Of course, for the surgeon, the smaller the cyst, the better it is to do it, and a single cyst is better than multiple cysts.