A Rare Case of Uterine Embryonal Rhabdomyosarcoma.

Background: Uterine sarcoma is a rare mesenchymal malignancy, and its preoperative diagnosis presents significant challenges, often resulting in the so-called occult sarcoma following surgery, based on the pathological diagnosis. Embryonal rhabdomyosarcoma of the female genital tract most commonly presents in pediatric patients and occurs in the uterine cervix. A pure uterine embryonal rhabdomyosarcoma presenting in an older adult patient is exceedingly rare. Due to its overall poor prognosis, early recognition of this unusual entity is crucial for patient care. Case: A 57-year-old woman presented with a single uterine mass and intermittent bleeding over the past 4-5 years. Office endometrial biopsies, conducted twice by other providers, reported either normal endometrium or inconclusive results; therefore, she was diagnosed and managed as having uterine fibroids for the past 3 years. Given the high suspicion of uterine malignancy, we counseled the patient with a plan for an abdominal hysterectomy and bilateral salpingo-oophorectomy. Meanwhile, we performed another endometrial biopsy under sedation to obtain an adequate and accurate specimen. This biopsy revealed high-grade malignancy, leading to the diagnosis of uterine embryonal rhabdomyosarcoma following the hysterectomy. She is currently undergoing chemotherapy with docetaxel and gemcitabine. Conclusion: Since there is no reliable laboratory or imaging study for preoperative diagnosis of uterine sarcoma, a high index of clinical suspicion is of the utmost importance to decrease the occurrence of occult uterine sarcoma, which is extremely difficult to differentiate from benign uterine fibroids.