Clinically Aggressive Uterine Epithelioid Leiomyosarcoma with Rhabdomyoblastic Differentiation and High Proliferation Rate: A Case Report.

BACKGROUND Leiomyosarcoma is the most common uterine sarcoma. Leiomyosarcoma is classified into conventional leiomyosarcoma, epithelioid leiomyosarcoma, and myxoid leiomyosarcoma. Leiomyosarcomas with rhabdoid features have been rarely reported. Herein, we report a case of uterine leiomyosarcoma with rhabdoid features. CASE REPORT A 58-year-old Korean woman presented with acute abdominal pain. Computed tomography and magnetic resonance imaging of the pelvis revealed a large solid mass in the posterior wall of the uterus that extended to the uterine cervix. The patient underwent total hysterectomy with bilateral salpingo-oophorectomy and tumorectomy. Microscopic and immunohistochemical examination of the tumor revealed leiomyosarcoma with rhabdoid features and high proliferation rate. Next-generation sequencing showed PI3K amplification and ERBB2 amplification. Postoperative abdominal and pelvic computed tomography performed 3 weeks after the operation showed a mass at the vaginal stump that was attached to the urinary bladder and rectum. The patient underwent pelvic exenteration of remnant vaginal stump, rectum, and urinary bladder with loop ileostomy, and was diagnosed with recurrent leiomyosarcoma. One month later, after the second operation, a 13-cm recurrent mass was noted on the computed tomography. Chemotherapy was not done and the patient died during supportive treatment 7 months after diagnosis. CONCLUSIONS This case, which is a uterine leiomyosarcoma with rhabdoid features and high proliferation rate, recurred very fast, within 1 month, and showed an aggressive clinical course. The molecular classification and postoperative therapy are not well established in uterine leiomyosarcomas. Further studies are required to clarify the clinical and pathological characteristics of leiomyosarcomas.