Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP) in Pregnancy: A Case Report from Omar Al Mukhtar General Hospital, Libya

Background: Smooth Muscle Tumors of Uncertain Malignant Potential (STUMP) are rare uterine neoplasms that occupy a diagnostic space between benign leiomyomas and malignant leiomyosarcomas. Their unpredictable biological behavior and ambiguous histopathologic features pose challenges in both diagnosis and management. STUMP tumors discovered during pregnancy are exceedingly rare, with limited documentation in the literature. Case Presentation: We report the case of a 24-year-old Sudanese primigravida who presented at term with no symptoms. Routine third-trimester ultrasound revealed a large adnexal mass, initially presumed to be ovarian. An elective cesarean section was performed at Um al-Razam General Hospital, Libya. Intraoperatively, a pedunculated, vascular mass was found attached to the posterior uterine surface, partially obscured by omental adhesions. The tumor was excised following fetal delivery. Histopathologic analysis confirmed the diagnosis of STUMP, based on moderate cytologic atypia, low mitotic index, and absence of coagulative tumor cell necrosis. The patient’s postoperative course was uneventful, and structured follow-up was initiated. Conclusion: This case highlights the importance of intraoperative reassessment when unexpected pelvic masses are encountered during pregnancy. It underscores the diagnostic limitations of antenatal imaging and the critical role of histopathology in confirming STUMP. Given the tumor’s uncertain malignant potential, long-term surveillance is essential. This report contributes to the scarce literature on STUMP in pregnancy and supports a multidisciplinary approach to management and fertility preservation.