Smooth muscle tumor of uncertain malignant potential (STUMP) is a rare variant uterine smooth muscle tumor with borderline features that reflect neither the benign leiomyoma nor the malignant leiomyosarcoma. The patient, a 30-year-old woman (gravida1, para1), presented with mild hypogastrium pain. As a result of detailed examination, we suspected a right ovarian multilocular cyst. Under the intraoperative view, the multilocular cyst grew under the right retroperitoneum, near the vicinity of the right uterine cardinal ligament. We conducted tumor resection, and microscopic analysis revealed STUMP in the center of the tumor wall. On a follow-up examination 3 months after the surgery, transvaginal ultrasound revealed a solid tumor measuring 3×5×4 cm on the right side of the uterus. We suspected the rapid recurrence of STUMP and conducted hysterectomy and salpingo-oophorectomy. The pathological diagnosis was that STUMP developed from the uterus. At a follow-up 15 months after the first surgery, the patient was alive and well with no evidence of recurrent or metastatic disease.

Authors: Yoko Tsuzuki, Iwaho Kikuchi, Michio Nojima, Koyo Yoshida

Key Words: Smooth muscle tumor of uncertain malignant potential, rapid recurrence, laparoscopy