From Presumed Leiomyoma to Stump: Laparoendoscopic Single-Site Hysterectomy with Contained Morcellation for a Large Unsuspected Borderline Smooth Muscle Tumor

Background: Smooth muscle tumors of uncertain malignant potential (STUMPs) are rare uterine neoplasms occupying the diagnostic continuum between benign leiomyoma and overtly malignant leiomyosarcoma. Their preoperative identification remains beyond the capability of current imaging modalities, and the diagnosis is almost invariably established through postoperative histopathological examination. The natural history of STUMP is highly variable, with recurrence rates ranging from approximately 7–27% and a documented potential for malignant transformation, underscoring the need for accurate pathological classification and long-term surveillance. Case Presentation: A 40-year-old woman with a history of hypertension presented with a 5-month history of progressive lower abdominal distension, urinary frequency, and menorrhagia. Transabdominal ultrasonography identified a large uterine fundal mass measuring approximately 10.89 × 8.96 cm. Preoperative laboratory findings demonstrated microcytic anemia. She underwent laparo-endoscopic single-site supracervical hysterectomy with bilateral salpingectomy. Histopathological examination revealed spindle cells with bland to mildly atypical nuclei, a mitotic count of <10/10 high-power fields, and focal necrosis, consistent with a diagnosis of STUMP. The patient remained free of recurrence over a 2-year follow-up period. Conclusions: This case illustrates the diagnostic challenge posed by STUMP in the preoperative setting and highlights the critical importance of thorough histopathological evaluation of all uterine smooth muscle tumor specimens. Minimally invasive hysterectomy with in-bag morcellation represents a feasible surgical approach, and long-term oncological surveillance is warranted given the risk of late recurrence and malignant transformation. Clinicians should maintain a heightened index of suspicion for borderline smooth muscle tumors when evaluating large or symptomatic uterine masses in premenopausal women.