A Sex Cord-Stromal Tumor Originating from the Mesorectum: A Case Report

Background: Ovarian sex cord-stromal tumors are rare neoplasms originating from the sex cords and stromal tissue of the ovary, with extraovarian occurrences being even rarer in clinical settings. In this report, we describe a case of an extraovarian sex cord-stromal tumor located in the rectal mesentery, highlighting the diagnostic challenges and management considerations associated with this rare presentation. Case presentation: A 33-year-old Chinese female presented due to a pelvic mass detected during examination. Color Doppler ultrasound revealed a cystic-solid mass located posterior to the uterus, with unclear borders from adjacent intestinal structures; gastrointestinal endoscopy excluded a digestive tract origin, prompting further pelvic Computed Tomography(CT) and Magnetic Resonance Imaging(MRI) evaluation. Imaging indicated a mass lesion anterior to the sacrum with multilocular septations, necessitating differentiation from mucinous tumors; in addition, changes in the left adnexal region suggested an endometriotic cyst. The patient underwent laparoscopic tumor resection; intraoperatively, the tumor was found tightly adherent to the rectal mesentery and primarily vascularized by mesenteric vessels, and was completely excised. Postoperative histopathology and immunohistochemistry confirmed the diagnosis of a sex cord-stromal tumor. The patient had an uneventful postoperative recovery, with no signs of recurrence observed at the 3-month follow-up. Conclusion: This case highlights the potential for ectopic occurrence of sex cord-stromal tumors, underscoring the need to consider this possibility during clinical evaluation and to distinguish it from other pelvic tumors. Incorporating imaging, intraoperative findings, and pathology is essential for accurate diagnosis and treatment planning.