A Rare Case of Uterine Smooth Muscle Tumor of Uncertain Malignant Potential with Bilateral Hydroureteronephrosis and Chronic Cystitis

Abstract

Background: Uterine smooth-muscle tumours of uncertain malignant potential (STUMP) present diagnostic and surveillance challenges, particularly when extensive pelvic involvement coexists with urinary tract obstruction. This report describes a patient with a large pelvic smooth-muscle lesion and bilateral hydroureteronephrosis. Case Presentation: A 36-year-old woman presented with lower abdominal pain and a history of recurrent urinary tract infections. Contrast-enhanced computed tomography on 19 January 2023 showed a 131 × 120 × 108 mm mass involving the cervix and uterus, with parametrial, ovarian, presacral and pelvic-wall involvement and encasement of both lower ureters. Ultrasonography-guided biopsy in February 2023 raised several differential diagnoses. Immunohistochemistry showed positivity for caldesmon, desmin and smooth-muscle actin, with a Ki-67 index of approximately 5%, supporting smooth-muscle differentiation. The patient received seven cycles of paclitaxel and carboplatin before undergoing radical hysterectomy with bilateral salpingo-oophorectomy, pelvic lymph-node dissection and omental sampling in May 2023. One further chemotherapy cycle and bilateral double-J stenting followed in July 2023. Postoperative PET-CT demonstrated suspicious pelvic and presacral deposits; however, a subsequent targeted biopsy showed no granuloma or malignancy. Ultrasonography during follow-up in 2024–2026 showed persistent bilateral hydronephrosis with stents in situ and no active disease. Conclusion: This case illustrates the need to interpret postoperative imaging alongside histopathological findings and to maintain coordinated gynaecological and urological follow-up when urinary tract obstruction persists.