BACKGROUND Retention of surgical items after a surgical procedure is not only a medical error, but can also lead to various unexpected complications and additional surgery procedures even years after the initial operation. CASE REPORT A 59-year old woman was referred to our hospital with intermittent pain in the lesser pelvis for about three months. She had undergone laparotomy for cholecystectomy 24 years ago and adnexectomy more than 30 years ago. CT-scan and MRI indicated a presacral tumor, most likely compatible with a presacral teratoma. A laparoscopic resection of the tumor was performed. Intraoperatively the tumor showed no clear capsule and could only be resected by fragments. The pathological report analyzed textile fibres, diagnosing a textiloma. The patient showed an uneventful postoperative follow-up. CONCLUSIONS Most likely, the textile fibres originated from a sponge, which was retained during adnexectomy 33 years ago. There are numerous reports of retained surgical items discovered years after the initial operation. In literature, there are several reported cases of transmural migration of a sponge into the intestine, stomach and bladder. In our case, the sponge must have migrated to the deepest point of the retroperitoneum, which appears to be quite unusual, as no comparable case reports could be found. This case stresses the importance of the surgeon's awareness to particular appearances of a retained surgical sponge from a surgical procedure performed even decades ago. Additionally, this case report stresses the importance of meticulous analysis of individual patient medical history.