Postmenopausal Enlargement of a Presumed Leiomyoma Revealing STUMP: A Diagnostic Pitfall with Important Clinical Implications-A Case Report

Background and Clinical Significance: Uterine smooth muscle tumors range from benign leiomyomas to highly aggressive leiomyosarcomas. Smooth muscle tumors of uncertain malignant potential (STUMP) represent an intermediate and diagnostically challenging category defined by borderline or discordant histological features. Their clinical management remains complex due to limited possibilities for reliable preoperative differentiation and the absence of clearly established surveillance protocols. The situation becomes particularly sensitive in postmenopausal patients, in whom tumor growth or abnormal bleeding raises concern for malignancy. Case Presentation: We report a 66-year-old postmenopausal woman presenting with persistent uterine bleeding and interval growth of a previously presumed leiomyoma. Transvaginal ultrasound demonstrated a heterogeneous intramural mass measuring approximately 5-7 cm, while endometrial sampling revealed inactive, atrophic endometrium without evidence of malignancy. Given the patient's postmenopausal status and progressive symptoms, total abdominal hysterectomy with bilateral adnexectomy was performed. Histopathological examination identified moderate cytological atypia, focal coagulative tumor necrosis, and mitotic activity of up to five mitoses per ten high-power fields, findings insufficient for leiomyosarcoma but exceeding those expected for a benign leiomyoma. A diagnosis of STUMP was established. Postoperative staging showed no residual or metastatic disease, and structured long-term follow-up was initiated. Discussion: This case illustrates the limitations of current preoperative diagnostic tools in distinguishing between benign and borderline or malignant uterine smooth muscle tumors. Clinical presentation, imaging, and endometrial sampling were not predictive of the final diagnosis. In postmenopausal women, enlargement of a presumed leiomyoma should prompt careful evaluation, as histological assessment after complete surgical removal often remains the only reliable method of diagnosis. The unpredictable biological behavior of STUMP and reported cases of late recurrence support the need for prolonged surveillance, even after apparently adequate surgical treatment. Conclusions: STUMP remains primarily a postoperative diagnosis and represents a persistent gray zone in gynecologic oncology. Postmenopausal tumor growth and abnormal bleeding warrant an individualized and cautious approach. Careful histopathological evaluation and long-term follow-up are essential to ensure early detection of possible recurrence and optimal patient management.